diff --git a/src/Database/Adapter/MariaDB.php b/src/Database/Adapter/MariaDB.php
index 0efa96df8..5e960247b 100644
--- a/src/Database/Adapter/MariaDB.php
+++ b/src/Database/Adapter/MariaDB.php
@@ -532,9 +532,16 @@ public function deleteRelationship(
 
         switch ($type) {
             case Database::RELATION_ONE_TO_ONE:
-                $sql = "ALTER TABLE {$table} DROP COLUMN `{$key}`;";
-                if ($twoWay) {
-                    $sql .= "ALTER TABLE {$relatedTable} DROP COLUMN `{$twoWayKey}`;";
+                if ($side === Database::RELATION_SIDE_PARENT) {
+                    $sql = "ALTER TABLE {$table} DROP COLUMN `{$key}`;";
+                    if ($twoWay) {
+                        $sql .= "ALTER TABLE {$relatedTable} DROP COLUMN `{$twoWayKey}`;";
+                    }
+                } elseif ($side === Database::RELATION_SIDE_CHILD) {
+                    $sql = "ALTER TABLE {$relatedTable} DROP COLUMN `{$twoWayKey}`;";
+                    if ($twoWay) {
+                        $sql .= "ALTER TABLE {$table} DROP COLUMN `{$key}`;";
+                    }
                 }
                 break;
             case Database::RELATION_ONE_TO_MANY:
@@ -545,9 +552,9 @@ public function deleteRelationship(
                 }
                 break;
             case Database::RELATION_MANY_TO_ONE:
-                if ($twoWay && $side === Database::RELATION_SIDE_CHILD) {
+                if ($side === Database::RELATION_SIDE_CHILD) {
                     $sql = "ALTER TABLE {$relatedTable} DROP COLUMN `{$twoWayKey}`;";
-                } else {
+                } elseif ($twoWay) {
                     $sql = "ALTER TABLE {$table} DROP COLUMN `{$key}`;";
                 }
                 break;
diff --git a/src/Database/Adapter/Postgres.php b/src/Database/Adapter/Postgres.php
index e52be9b53..ff3416f1a 100644
--- a/src/Database/Adapter/Postgres.php
+++ b/src/Database/Adapter/Postgres.php
@@ -525,25 +525,34 @@ public function deleteRelationship(
         $relatedTable = $this->getSQLTable($relatedName);
         $key = $this->filter($key);
 
+        $sql = '';
+
         switch ($type) {
             case Database::RELATION_ONE_TO_ONE:
-                $sql = "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
-                if ($twoWay) {
-                    $sql .= "ALTER TABLE {$relatedTable} DROP COLUMN \"{$twoWayKey}\";";
+                if ($side === Database::RELATION_SIDE_PARENT) {
+                    $sql = "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
+                    if ($twoWay) {
+                        $sql .= "ALTER TABLE {$relatedTable} DROP COLUMN \"{$twoWayKey}\";";
+                    }
+                } elseif ($side === Database::RELATION_SIDE_CHILD) {
+                    $sql = "ALTER TABLE {$relatedTable} DROP COLUMN \"{$twoWayKey}\";";
+                    if ($twoWay) {
+                        $sql .= "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
+                    }
                 }
                 break;
             case Database::RELATION_ONE_TO_MANY:
                 if ($side === Database::RELATION_SIDE_PARENT) {
                     $sql = "ALTER TABLE {$relatedTable} DROP COLUMN \"{$twoWayKey}\";";
-                } else {
+                } elseif ($twoWay) {
                     $sql = "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
                 }
                 break;
             case Database::RELATION_MANY_TO_ONE:
-                if ($side === Database::RELATION_SIDE_PARENT) {
-                    $sql = "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
-                } else {
+                if ($side === Database::RELATION_SIDE_CHILD) {
                     $sql = "ALTER TABLE {$relatedTable} DROP COLUMN \"{$twoWayKey}\";";
+                } elseif ($twoWay) {
+                    $sql = "ALTER TABLE {$table} DROP COLUMN \"{$key}\";";
                 }
                 break;
             case Database::RELATION_MANY_TO_MANY:
@@ -564,6 +573,10 @@ public function deleteRelationship(
                 throw new DatabaseException('Invalid relationship type');
         }
 
+        if (empty($sql)) {
+            return true;
+        }
+
         $sql = $this->trigger(Database::EVENT_ATTRIBUTE_DELETE, $sql);
 
         return $this->getPDO()
diff --git a/src/Database/Database.php b/src/Database/Database.php
index ca7920ac1..bc232ede1 100644
--- a/src/Database/Database.php
+++ b/src/Database/Database.php
@@ -2186,9 +2186,17 @@ public function deleteRelationship(string $collection, string $id): bool
 
             switch ($type) {
                 case self::RELATION_ONE_TO_ONE:
-                    $this->deleteIndex($collection->getId(), $indexKey);
-                    if ($twoWay) {
+                    if ($side === Database::RELATION_SIDE_PARENT) {
+                        $this->deleteIndex($collection->getId(), $indexKey);
+                        if ($twoWay) {
+                            $this->deleteIndex($relatedCollection->getId(), $twoWayIndexKey);
+                        }
+                    }
+                    if ($side === Database::RELATION_SIDE_CHILD) {
                         $this->deleteIndex($relatedCollection->getId(), $twoWayIndexKey);
+                        if ($twoWay) {
+                            $this->deleteIndex($collection->getId(), $indexKey);
+                        }
                     }
                     break;
                 case self::RELATION_ONE_TO_MANY:
@@ -2199,9 +2207,9 @@ public function deleteRelationship(string $collection, string $id): bool
                     }
                     break;
                 case self::RELATION_MANY_TO_ONE:
-                    if ($twoWay && $side === Database::RELATION_SIDE_CHILD) {
+                    if ($side === Database::RELATION_SIDE_CHILD) {
                         $this->deleteIndex($relatedCollection->getId(), $twoWayIndexKey);
-                    } else {
+                    } elseif ($twoWay) {
                         $this->deleteIndex($collection->getId(), $indexKey);
                     }
                     break;
diff --git a/tests/e2e/Adapter/Base.php b/tests/e2e/Adapter/Base.php
index 6eb5f4f37..5fd42ea15 100644
--- a/tests/e2e/Adapter/Base.php
+++ b/tests/e2e/Adapter/Base.php
@@ -78,6 +78,169 @@ public function testCreateExistsDelete(): void
         $this->assertEquals(true, static::getDatabase()->create());
     }
 
+    public function testDeleteRelatedCollection(): void
+    {
+        if (!static::getDatabase()->getAdapter()->getSupportForRelationships()) {
+            $this->expectNotToPerformAssertions();
+            return;
+        }
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createCollection('c2');
+
+        // ONE_TO_ONE
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_ONE,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_ONE,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c2');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_ONE,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_ONE,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        // ONE_TO_MANY
+        static::getDatabase()->createCollection('c2');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_MANY,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_MANY,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c2');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_MANY,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_ONE_TO_MANY,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        // RELATION_MANY_TO_ONE
+        static::getDatabase()->createCollection('c2');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_MANY_TO_ONE,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_MANY_TO_ONE,
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c2');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_MANY_TO_ONE,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c1'));
+        $collection = static::getDatabase()->getCollection('c2');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+
+        static::getDatabase()->createCollection('c1');
+        static::getDatabase()->createRelationship(
+            collection: 'c1',
+            relatedCollection: 'c2',
+            type: Database::RELATION_MANY_TO_ONE,
+            twoWay: true
+        );
+
+        $this->assertEquals(true, static::getDatabase()->deleteCollection('c2'));
+        $collection = static::getDatabase()->getCollection('c1');
+        $this->assertCount(0, $collection->getAttribute('attributes'));
+        $this->assertCount(0, $collection->getAttribute('indexes'));
+    }
+
     /**
      * @throws Exception|Throwable
      */