1) razor blade would do fine (number 11).
2) sharpened screwdriver (flathead)
3) unsharpened small screwdriver (flathead, eyeglass or jewelers)
4) round front flush cut nail clipper (pushed hard into the cap)
5) knife, just use the tip
6) heat up a pin, paperclip, thin metal rod and push it down
7) a file
sand paper
9) dremel or any small rotary type tool (almost any attachment would do it)
10) chisel small, large
11) make a chisel (use dremel to sharpen a piece of metal)
12) flush cutters
13) Drill a hole or twist a hole with an x-acto knife (number 11 blade)
14) try a tiny bit of acetone on it
15)....
.........sorry, I am really bored right now =P
Whatever you use there will be either some clean up still required and/or a small or large spot with a different texture. You could remedy this by changing the texture of the whole key (and most likely lose the letter printed) or selectively adding a small bit of texture back in.
I guess if I had to do this and had a very limited range of tools available, I would just use a sharp knife or x-acto and shave it down lightly and slowly.
