Since it's attached to the glass, it should be easier than if it were attached to rock work. If the ice cube doesn't work, take a credit card and carefully slide it between the anemone's foot and glass. It'll take some time, but it'll work great.
thanks everyone. I tried an ice pack from the outside of the tank and it didn't work so i put on a rubber glove and gently used my fingernail to seperate it from the glass it only took a few seconds for it to release once again thanks for everyones help