mix up a kalkwasser paste and suck it up with a syringe and carefully apply only a small amount to the polyps 'don't go crazy it will jack up your KH!" but this will also kill aiptasia, palys that grow to fast.. just about anything!
If the rock is easily removed you could put it in a bucket of old saltwater ( after water change ) and let sit in the dark. The majano will start to move towards any light available and loosen its footing on the rock. After a day or so you can take a turkey pastor and blow it off the rock.