diff --git a/app/auth/views/activate.py b/app/auth/views/activate.py
index 08d9f5dd..520903f2 100644
--- a/app/auth/views/activate.py
+++ b/app/auth/views/activate.py
@@ -41,7 +41,7 @@ def activate():
     login_user(user)
 
     # activation code is to be used only once
-    activation_code.delete()
+    ActivationCode.delete(activation_code.id)
     db.session.commit()
 
     flash("Your account has been activated", "success")
diff --git a/app/auth/views/reset_password.py b/app/auth/views/reset_password.py
index 0c66da00..261f20a4 100644
--- a/app/auth/views/reset_password.py
+++ b/app/auth/views/reset_password.py
@@ -49,7 +49,7 @@ def reset_password():
         user.activated = True
 
         # remove the reset password code
-        reset_password_code.delete()
+        ResetPasswordCode.delete(reset_password_code.id)
 
         db.session.commit()
         login_user(user)
diff --git a/app/developer/views/client_detail.py b/app/developer/views/client_detail.py
index 1c9e4b05..7e0c201d 100644
--- a/app/developer/views/client_detail.py
+++ b/app/developer/views/client_detail.py
@@ -57,7 +57,7 @@ def client_detail(client_id):
 
             # replace all uris. TODO: optimize this?
             for redirect_uri in client.redirect_uris:
-                redirect_uri.delete()
+                RedirectUri.delete(redirect_uri.id)
 
             for uri in uris:
                 RedirectUri.create(client_id=client_id, uri=uri)
diff --git a/app/developer/views/index.py b/app/developer/views/index.py
index 4e398341..716ccf9e 100644
--- a/app/developer/views/index.py
+++ b/app/developer/views/index.py
@@ -21,7 +21,7 @@ def index():
                 flash("You cannot remove this client", "warning")
             else:
                 client_name = client.name
-                client.delete()
+                Client.delete(client.id)
                 db.session.commit()
                 LOG.d("Remove client %s", client)
                 flash(f"Client {client_name} has been deleted successfully", "success")
diff --git a/app/models.py b/app/models.py
index bfce2305..6365ec90 100644
--- a/app/models.py
+++ b/app/models.py
@@ -57,8 +57,9 @@ class ModelMixin(object):
     def save(self):
         db.session.add(self)
 
-    def delete(self):
-        db.session.delete(self)
+    @classmethod
+    def delete(cls, obj_id):
+        cls.query.filter(cls.id == obj_id).delete()
 
     def __repr__(self):
         values = ", ".join(
diff --git a/app/oauth/views/token.py b/app/oauth/views/token.py
index eab47ef2..90368982 100644
--- a/app/oauth/views/token.py
+++ b/app/oauth/views/token.py
@@ -64,7 +64,7 @@ def get_access_token():
     db.session.add(oauth_token)
 
     # Auth code can be used only once
-    db.session.delete(auth_code)
+    AuthorizationCode.delete(auth_code.id)
 
     db.session.commit()