Spray penetrating oil on the bolt and let it soak
Clean the area around the bolt
Try loosening it with the correct size wrench or socket
Use locking pliers if part of the bolt is exposed
Tap the bolt lightly to help break corrosion
Apply heat to the surrounding metal if safe to do so
Use a center punch to mark the bolt if drilling
Drill a small pilot hole into the bolt
Use a left-hand drill bit if available
Insert a screw extractor and turn it counterclockwise
Drill the bolt out completely if extraction fails
Re-tap the threads if they are damaged
Use a thread insert if the threads are stripped
Replace the bolt with a new one after removal