i suggest getting a pro do it, but most places might not only pull your glass

but if your bound and determined to do it yourself, you will need to buy a "cold knife"(blade w/ handle and cable) to get behind glass and cut through the urethane..
you will also need a razor knife(long blade will help) to cut some sections that cold knife wont reach..

i think you can purchase these at autozone,advance,places like that.
and there is proper steps to reinstall the glass, thats another reason i suggest calling the pros