ther is a product called "Goo be gone"...sort of a solvent for just such adhesives....another is lestoil, a laundry supplement....pull of as much as the sticker as you can and let the product soak in....
as a collector of wood bats, these 2 things work best for me on the newer player model bats.... On my older bats, I never use any solvents.....
Hope this helps...