First, what is it stuck on? If it’s rusted on hub then the BFH (big fucking hammer) advise is good. If it’s stuck because the shoes have worn a grove in the drum and it’s stuck on the shoes, BFH is a bad idea.
On every car I’ve seen with drum brakes there is an adjustment window on the back side. It should be a little rubber plug, around an inch wide by 1/4" tall. Pull that out, get a flashlight, and locate the little gear wheel inside. Turning it one way will back the shoes off. You’ll have to experiment to figure out which way, and I guarantee you’ll be pissed when you work real hard to turn that little bastard and all of a sudden you realize the rotor is on even tighter because you went the wrong way.
There is a special tool that looks like a screwdriver bent into an S for doing this, but I’ve done it with just a regular screwdriver. There is a little arm that you’re suppose to lift up to make the wheel turn easier, but I’ve always had luck just forcing it. If the shoes are what’s holding it on, you’re going to bend the shit out of something if you just try to force it off with a puller.