Sometimes a parking brake can stick due to rust. Usually it breaks free pretty easily when the car is put in gear and you get on the gas. In this case the cable could be stuck and not releasing the brake. Or, there is some broken parts in the locked wheel and debris is wedged in the drum somehow jamming the wheel.
If you can’t get the car moving just by some rocking back and forth action, then you’ll have to pull the wheel and then the brake drum to find out the problem. Since this is all locked up at the moment it won’t come apart easily. If you’re not mechanical I’d get the car towed to a shop. After jacking up the locked wheel you should put it on a jack stand before working on it. You are going to be doing a lot of banging and yanking on the wheel and drum. It is too dangerous doing this kind of work with the jack supplied with the car. Also wear eye protection as you work on this one.