What a fun chore...when we took the doors off the Stude, we had several bolts that didn't want to budge...

We ended up using an impact hammer on some, and for a couple of them, we just drilled the center out of the head of the bolt to make it come loose...just make sure you stay centered up, so you don't mess up the hinge too...

Sometimes squirting them with a little joy juice ( WD-40 or something similar) will help work them loose a bit, so you don't have to strain yourself as much...

Or, like Henry said, you can cut em' off too...

Good luck !