You could drill out the lock but... Once you remove the latch and lock from the inside you can bolt the latch back in place. Then you'll operate it with a flathead screw driver through the lock hole until a new lock cylinder or key comes along.
Right now a locksmith can cut a key or rekey that lock cylinder. Once its drilled its trash.
would a locksmith be able to rekey it while it's still intact and in the car? That above all else would probably be the easiest and least painful scenario. I didn't think that could be done but if it can be ...