How can when can I rescind a scholarship? I've got 3 walk ons and they all suck.

Walk ons aren't scholarship players. You can't cut them. And they don't return next season. You will automatically have the resources for them during recruiting

But you can cut players when the hiring process ends. If you want to make cuts, it's best to do so before the first cycle of RS2 processes. But for now, those walk ons will be on your team all season. You don't have to play them of course.