If the brakes are that far gone, the shoes may be worn into drums and that may be why they aren't letting go very easily. A couple things you can do. First make sure your e-brake is released, and then if it doesn't feel slack enough (feel the cable firmness at the rear axle) disconnect the cable at the back of the drum. With the four axle nuts removed (center of the drum) put the tire back on, just leave at least a half inch of space between the lugs and the wheel. Make sure you use enough threads so the lugs don't strip. Make sure the jack stands are sturdy and the vehicle is stable. Use the wheel as a slide hammer to 'yank' the drum off.
If after 3-4 good whacks it doesn't pull loose, bleed the brakes at the rear wheels, and try again.
Another way is to remove the nuts as above, but put the tire back on like normal. Then use the factory jack between the inner fender (towards body/floor area) and the back of the tire. Be careful, because the tire can come off with enough force to surprise you.