If it is a passenger side bolt or not near the tank then heat is good but otherwise cut it off.
The nut portion is already screwed up on that one and will need replacement, in fact if all the bolt came out hard then all of the nuts should be replaced, maybe the bolts too.
When I replaced my bed I had to cut off two of the bolts and used all Ford replacements but if I were to do it again I would use standard hex head bolts, maybe either use the ford Nuts or get a similar replacement, stainless steel would be good or a lot of anti-seize.
4x4, 5sp, Std Cab, Stepside, E4 Red
4” Lift - Coil-Overs, 6” SkyJacker Leafs - No Blocks (Mistake)
31 Spline FX4 Rear Axle, 4.56s and OX Locker, Hurst Shifter w/Optional Stick and "Made by Grev" alignment adapter