[Answered ]-Unable to delete User objects in Django

Problem here is not in your code but in your database state. Looks like you added django reversion app. Which adds new Models in your project. Run

python manage.py syncdb

or if you in 1.8+

python manage.py migrate

Update

If this doesn’t help than there are no migrations for your 3rd-party app you need to first create them with

python manage.py makemigrations name_3rd_party_app

Be careful with creating migrations on 3rd-party apps. When you run makemigrations it creates migrations in 3rd-party app package. So it won’t be in your code. And after you deploy it, or other user uses it there are will not be this migrations. So you need to supply custom path for created migrations with https://docs.djangoproject.com/en/1.9/ref/settings/#migration-modules

And then run migrate