I replaced the decals on the front and rear of my 5er several years ago. Some came off relatively easy with heat gun and plastic scraper. Some of the worse ones would not. I ended up using a 3M eraser wheel. That worked well.
On another forum I frequent someone was trying to sell his 5er that he had removed all the decals. Large, white, and very plain looking. No eye appeal at all. No reasonable offer so he very generously gave it away to a person in need. Don’t know if the lack of decals affected the sale or not.