first, you will have to remove the clowns, as they will attack you to protect it.
then do not just go in there with gloves and try to tear it off!!! you will tear the foot and it will kill the anenome.
to remove them, go in with gloves and a sealed plastic bag with ice cubes in it.apply the ice to the foot where it is attached, and it will start to change colors and shrink up. after some time, it will start to let go. if it is on a small rock you can pick the rock up and hold it upside down while applying the iCe, which will help you. have a lot of ice on hand and make sure tank water stays out of the ice bag, or it will melt much quicker.