Do NOT pick them off!!! Any fragmented remnants left of the anemone will grow to become more anemones. Best off to chemically kill them..... use the search function for aipstasia and you will probably find hundreds of threads on this forum alone. There are many different methods of eradication..... hot vinegar or lemon juice, Joe's Juice, Aipstasia-X, Kalk paste. Any of these injected directly to the anemones mouth will typically kill it.