If drum is rusted on how should it be removed?

Drum as in drum brakes? Several things to try. In extreme cases use a file or sand paper to clean up the hub that the drum goes over. Spray it with some WD40 or similar lubricant. Tapping on the drum lightly while you pry on the back may help. Some cars, imports mainly have two threaded hole in the face of the drum. Screw the right size bolt into each hole and tighten them back and forth. This will force the drum off. You can use a propane torch to heat up the drum right around the hub.

If you use a pry bar or large flat screwdriver to go between the drum and the backer plate and then pry out on the drum. Hold the pressure on the drum and tap the face of the drum with a hammer. Not too hard as you can break the drum. Sooner or later, it will pop just a bit. Turn the drum 1/4 turn and do it again. Eventually, the drum will come off.