After deleting plugin, functionality still on sign up page

After realizing that this plugin does not work on multisite (not sending user password, no moderation, etc) I tried to disable and delete it, and I deleted the test user I created.

However when I go to re-sign up, the sign up page still says the username is reserved, and when I create a brand new user it still says it will be sending an activation email even though the plugin is deleted and there should no longer be an activation email.