Often for cosmetic reasons it is desirable to remove old torn cruddy or just plain ugly decals from your bike. This has been discussed many times and below are a few agreed upon means to remove your old decals
Heat & Pull
Applying heat will begin to melt the glue making it easier to remove the decals. A hairdryer is sufficient, a heat gun probably overkill. you want to apply enough heat to loosen the glue but not so much as to begin melting the decal itself. Too much heat and it will tear the decal. Once it's heated begin to peel up the corner with a razor blade until there's enough to grab and then pull slowly by hand. The remaining glue can then be removed with Goof Off or other adhesive remover or also with WD40 or gasoline. Clean off any remaining remover residue with windex or soapy water and you're lookin good!
Can be done with or without heat. Basically you want to peel back the edge of the decal the whole way across and then peel it back against itself to keep a very tight radius where it's pulling. You're pretty much holding the face of the decal that you've already pulled against the face of the rest and rolling/peeling it back. WD40 on the exposed glue can help it let go.
You can buy a decal eraser tool which attaches to grinding wheels or drills and is basically a rubber block that rubs and pulls off the decals. running these at 1500-3000 rpm and applying light pressure should take your decals off quickly and easily. Then just finish up with some WD40 and soapy water to remove the leftover residue. BEAUTIFUL!