If the wheel can't be knocked off (maybe something is wedged in between the inside of the wheel and rotor), try: If you can wobble the wheel, can you turn it slightly to gain access to the rotor retaining screw through a lug nut hole? If so, remove then take off the caliper bolts and brake line so the whole assembly comes off.

All this said, I am doing this from memory so I am not responsible for forgetting why this crazy idea won't work..