They are called pop or thumper bumper shields.

They are normally made of of mylar, fish paper, or other plastics. Get rid of them.
Cut them out, if need be.

They collect dirt underneath them and ruin playfields.
It was an industry mistake.

For the adhesive style and if naphtha does not directly work, take a paper towel and lightly soak the area in "Goo Gone" (NOT "Goof Off"), for a couple of minutes and carefully use a flat tip solder tool to peel it up. Rinse and repeat until paper is removed. Clean all traces of residue with alcohol or naphtha. With a little effort, and not over soaking, the glue bond will be weakened.