fixture not being removed after unit test?

I am experiencing a problem with fixtures. I have two test suites, one that tests a login controller, and one that tests a signup controller. What's happening is I have to load in fixtures for the Login controller tests (:emails, :users ). That test suite works fine.

But when it does the test for the Signup controller, those emails and users are still in the database so some of my tests error out (error when a user already exists).

how can I make the loaded fixtures drop out before moving onto another test suite.