Yes, I always take the rock out of my tank whenever I decide to glue a bunch of different Zoanthids onto the same rock. Its way easier for me to work on them outside of the tank and I prefer using superglue to the reef epoxy. To take them off the disc I usually just pry them off gently with my fingers. More times than not, just a little force and the rock that the Zoanthids are on just pop right off the frag plug. If you have a frag that is hard to separate from the disc you can just use a small screwdriver or anything with a flat head to pop it off. Just make sure you don't miss and hit the Zoanthids and they will be fine. Sometimes I will have them out of the water for up to 5 minutes with no ill effects. The purple and orange ones I pictured above are probably my hardiest Zoanthids I have and when they have been out of the water the polyps just stay open.