Are you sure that the Drum is free of the Axle? If not take a 3 or 5 lbs malet and hammer outter edge of the face(flat part) of the drum. I usually start at 12 o'clock then 6,3,9 and keep moving around the drum. Once the drum is free from the axle and if it still won't come off try this. Look at the backside of the Backing Plate. Look for the anchor pins that hold the shoes to the backing plate (should be at 6 and 9 o' clock positions). If possible grab hold of the pins (from the back side) pull them toward the opposite wheel and the cut them with a small die grinder or side cutters. This should allow you to pull the drum and shoes off at the same time.
Good luck
