When you have a nail or screw you can't seem to remove, cutting it down might be your best option. If you don't have a metal saw around, this trick will let you use the backside of a normal woodworking hand saw and avoid damaging the teeth.
This video from the Shake the Future YouTube channel demonstrates a quick and easy tip for turning the backside of your woodworking hand saw blade into an impromptu metal blade. Take a hammer, crowbar, screwdriver, or file and give the flat backside of your hand saw's blade some good hard whacks to create some divots.
Be sure to space them out and you'll manage to create some very small, but useful saw teeth that can make their way through metal. Now you can saw through the nail or screw normally using the backside of your hand saw blade, and keep the normal teeth protected.