There is a ridge of rust built up that is stopping it from coming off. They can be a real pain to get off because of it. Another thing to check is that the parking brake is releasing fully. The linkage likes to seize and not release fully. Take a hammer and give it a few taps where the cable attaches to the released position.Update,
Rotated adjuster fully in both directions, obviously one direction applies the brake and the other removes the parking brake.
still cannot get this rotor off! Any ideas?