Indeed Kalk paste will kill them, if they are not something you want or something you want to frag and give away. Just shoot it into their mouth like you would a aiptasia.
I use a good pair of tweezers and pull them off. If you put them in a cup with rock rumble they will attach to rock and you can give them away. You have to watch and pluck for the next couple weeks if any reappear. This doesn't kill the zoos just helps to relocate them. But you can throw them out if you want. This method helps keeping them from releasing any toxins into the water also.:squigglemouth: