Bumper Sticker Removal

The surprising answer, at least to me, on how to remove bumper stickers is to heat them with a hair dryer, or better yet, a heat gun.  It just softens the glue enough to make them (at least relatively) easy to pull off.  Any remaining glue can be removed with a product like Goo Gone For Cars.

https://www.cars.com/articles/how-to-remove-a-sticker-from-your-car-1420663070247