 <p>In my case I had two models User and Admin and I am sticking with Devise, but I had a name collision issue with ActiveAdmin that requires me to remove the Admin model. But because there were so many references to Admin in devise, I had to take the steps below. I think it answers the original question above as well, though. I believe the correct way to do this is:</p> <p>1.Find the devise migration for the user model and roll it back <strong>[IMPORTANT: IF you DON'T want to remove the user table associated with Devise, then SKIP THIS STEP]</strong>:</p> <p><code>rake db:rollback VERSION=&lt;insert the version number of the migration&gt;</code></p> <p>example: <code>rake db:rollback VERSION:20110430031806</code></p> <p>2.Run this command to remove Devise and associated files. <code>rails destroy devise Admin</code> (if Admin is the name of the model with user accounts).</p> <p>This produces this output:</p> <pre><code>invoke active_record remove db/migrate/20110430031806_devise_create_admins.rb remove app/models/admin.rb invoke test_unit remove test/unit/admin_test.rb remove test/fixtures/admins.yml route devise_for :admins </code></pre> <p>3.To completely remove Devise, you need to remove all references to it in your models, controllers and views. This is manual work. The answer above provides good details for finding this cruft, but was incomplete for my purposes. I hope this helps someone else.</p>