So your project's over and you want to go your separate ways. Or maybe you're just ready to strike out on your own.
If you're ready to move on, simply ask your admin to remove you from the Studio team. Removing a member from a team is done under the Studio Management Tab.
They'll only be billed for the time you were part of the Studio. If you do leave, you and the admin will have to discuss what happens to the files you created while a member.