Torx screw holds em on . Can't remember the size off the top of my head , might be a 25 or 30 .Sometimes they feel like they are still stuck on after you've taken the screw out , it'll probably be rusted on , give a few hard hits with a hammer , or try with the screws undone and the caliper still on pressing the brake pedal , this can sometimes help it to come off . Copper grease on the hub before you fit the new discs will help next time you want to change em .