If you have an extension with a clamp, remove the mag. tube clamp first.
Wear eyepro. Keep the saftey on.
Unscrew the extension or tube cap (the cap may have a spring retainer or something-I don't know for sure). It is locked in place via detent stud so no tools needed) Be sure you gave a good grasp on the cap or extension because it will want to launch off.
Slide the action open about half way (You may begin to feel a little resistance at this half-way point).
Slide the bbl. out, off the end off the mag tube.
Push in the elevator up with your fingers and you will feel spring clips on either side of the inside of the rcvr.
Push in on the spring clips (one, then the other) while moving the forend/pump handle foreward to unlock and remove the pump handle and bolt from the rcvr. Slide it up and off of the mag tube.
If you need to replace just the stock material, you'll need a special tool to unscrew the locks that hold the metal part with the arms (can't remember the name) to the wood or synthetic part.
I think most replacement handles come with a removal tool but I could be wrong. It's just a wide, flat piece of metal from what I've seen. If you need to do it often, you can buy a forend key/tool.
It should take less time than it took me to type this.