If you can remove the rocks, a syringe and a bottle of muriatic acid, and then a good rinse, is your best bet by far.
If you can't remove the rocks, the Joe's Juice and other products on the market I have found to be mediocre at best. Far better is a maximum strength kalk mix (a small plastic cup with 2 tbsp of kalk powder mashed into a wet paste. Heat it in the microwave until bubbling, then use a thick guage syringe to pierce into and saturate the anemones. Be prepared to go through several syringes as they will clog, get the largest size guage you can.
Failing that, peppermint shrimps are a maybe. Some will eat them, others will ignore them entirely. Ditto CBBs, Racoon Butterflies, and Pakistani Butterflies. All reputed to eat them. Individuals will vary. Only one animal is certian 100% to eat them ... Berghia Nudibranchs. Can be hard to find depending on where you are. They can be pricey as well. But they will eat them until they are all gone. And then the buggers will die unless you find them a new home or new supply of aiptasia.
The good news on the Berghias is they breed like crazy. So, after you solve your problem, keep a couple infested rocks in a separate system, and breed and sell them.