Some VERY careful work with a razor blade will do it. Not too hard to get the hang of, but be sure to use some dishsoap and hot water in a spray bottle, or some commercially produced products for removing sticker goo with it. There are some orange-based products out there that actually work and won't hurt your paint. If you use a solvent, remember, you will have to re-wax at the very least and repaint the clearcoat more likely.
Do NOT use any scrubber pads, or you WILL be repainting. Razors actually work very well. You can practise on a peice of glass, like a spaghetti sauce jar. Get comfy peeling the lables from them and you can think about doing it to your truck. Just watch the corners, they gouge, Keep the blade flat and go slowly and you will be fine. They do make plastic scrapers for this too if you can find them. Check at body shop supply stores or at a janitorial supply too.