It depends on the surface they are on and how determined you are. I guess I don't see anything wrong with book inscriptions. Do they do this to a doll? A truck?
I can get sharpie off/out of many things but it doesn't mean the stuff I got it off is the same after it is done. My process is usually for proving which pen made what mark and when. The original material is usually destroyed in the process (or you can really tell that I removed it).
I would advise to not try to remove the marks and treat the underlying issue. Get help for the OCD instead. What seems like a little quirk now can be very devastating later in life.