So, I tried asking this question on Reddit, and all I got back were trolls and unserious replies. 😒
So, does anyone know how I can remove the sticker residue on these games without accidentally rubbing the factory codes off?
A razor blade should get most of the physical residue off, especially if you hit it with a hair dryer. Warm adhesive is easier to scrape off than room-temperature. If you don't trust your manual dexterity, then try one of the other methods described by other commenters.