If the wedge(s) can be removed, then tap the handle out and you're ready to rehandle. If the wedge(s) can't be removed easily enough, or if the handle has been glued as well, I use a piece of round bar slightly smaller than the eye, place the hammer in the post vise, and use the round bar and a 6 lb hammer to drive the handle out by punching it out. Sometimes the handle can be reused as is, most times you have to reshape the eye end for a proper fit. I do that on the belt sander. Usually the handle will be loose already and that is why you would be reusing it, so it's easy to knock it out of the hammer head. When replacing the handle, a wood wedge in line with the hammer head and a metal wedge 45º to that should suffice if all fits properly.