This is really simple, just grab an expo marker...
These are just cheap plastic dividers from school several years ago. I'm not sure if its pen or sharpie but either one would come off.
Cover the writing completely with an expo marker. It doesn't have to be black.
Quickly wipe off the marker with a tissue or napkin, and voila! The previous writing should be gone or much lighter! *note* this may not work for everything, no guarantee but it's worth a shot!