Let him go, but don't try to feed him, you can't make an anemone stay where you want. Mine BTA wonder for a week all over the tank, it was facing the back and finally surface facing the top and front of the tank. I then started feed it bits of shrimp, so the anemone thinks it's a good spot because it is finally finding food and decent lightig, it's been there for a month and not moving!
Remember if it's not happy it will move.