It takes a while, but if you don't have to worry about it touching corals, you can move its light source. I had a condy in a 20 gallon that I wanted to get rid of. I moved the lighting fixture to the side and waited for the anemone to move towards the light. While it's moving, it's not attached to the rock that well and is easy to remove. It took a couple of days though, and you have to catch it while it's moving, not after it's moved to a new spot it likes.
But if you have corals in the tank, I wouldn't try it that way.