Seatbelt Removal

I'm guessing no impact or one strong enough... that's ok

Do you have a piece of pipe that will go over the breaker bar to use as an extention? (beware, I have broken many a breaker bar doing this)

Also, if there is nothing around it to catch fire get a torch on it then reef on it with that breaker bar!

If all else fails, like Johny Dart said "grind it off and get new bolts and nuts"