Got any Calcium hydroxide around? Mix up a limewater slurry and get a hypodermic needle without the needle and inject the mixture into its mouth. Make sure you have low or no flow while doing this so that it takes it in internally and voila, gone. Small ones you can see may still grow so you may need to watch carefully and treat again soon but you can get on top of them.
Or if you are lazy just get a Copper banded Butterfly, I have a pretty good 3 month growth of them in the 185 last week, added a butterfly and within one week no aiptasia remain visible. Simply amazing.