Rookie mistake

[Haloreef]

Could you remove the rock from your display and with a hammer and chissel, remove the affected area? You could then trade it to some one who would like it. (Not me, I hate the stuff.)
Pealing it off is labour intensive and not very effective. Any small pieces left stand a very good chance of returning. Pieces that may get away from you may start other colonies.
Like I said I hate the stuff. Yes it's "pretty" but it ain't SPS!
Good luck.