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.