Like stated above, make sure the adjusters are backed off so the shoes are not causing the problem. IF the adjusters are stuck you can take the retainer washer off the pin and pull drum and shoes together, although this does not work very well.
The EASY way, and I do mean EASY, to get drums off rear axles is to heat the drum with a propane torch right around the wheel stud area. DO NOT HEAT THE AXLE HUB itself. You are only wanting to heat the drum to expand it slightly so it will slip right off of the hub. You do not need a lot of heat--just slightly more than what you can stand your hand on for a second or two.
In a particularly stubborn case I once had to run a water hose on the axle/drum assy until the axle was as cool as the water coming out of the hose. I then used a torch as described above and the drum almost fell off.
BTW this trick works on anything with outboard drums, from pickups to semi trucks.
