[Overdriven]

Noooo!! Don't do that! Its what helps keep the rotor from flying apart and taking out the windings in your motor when it does. Simplest thing to do is take some epoxy and go over the area where the piece already fell off to help prevent more from coming off.

If you're going to take more off, take a hobby knife and cut around the base of the part that already fell off. This will help you take off the "chunk" that didn't break off without disturbing the rest of the wrap. If you don't want to or can't find some carbon/kevlar thread to re-wrap that section, apply a little expoy at the edge of the old wrap to help keep it from coming undone.