I have had to deal with this situation a few times, to large of rock to remove so have just taken my large Tongs and firmly grabbed them near base and pulled them off. I use a small container with some water in it to deposit the unwanted removed/squished palys and occasionally clean off Tongs. I crank up my Ozone for this and feel safe in removing up to several dozen at a time. You could run a temporary HOB filter with fresh Carbon or just fresh bag in sump to help reduce toxins as well. With a little practice you can get pretty good at just applying the right pressure to pull them off cleanly, sometimes multiples attached at polyp base.
Cheers, Todd