Remove rear wheels. Remove both rear caliper and brake pad assemblies. Hang them aside. On the face of the rear rotor check to see if there is an Allen screw securing rotor to axle - remove screw. Be sure emergency brake is not on. Remove rotor. If it doesn't want to come off, emergency brake is probably hanging it up. Locate emergency brake adjuster through wheel bolt hole in the face of the rotor (rotate axle and rotor using a light to locate the star adjuster). Using a screwdrive back off adjuster to release emergency brake shoes. Try again to remove. If it still doesn't come off, hit the face of the rotor at hub with a hammer (not kidding!) as rust may be holding it in place.