I would use a plastic knife and slowly seperate portions of the anenomes foot from the glass until its completely off. A razor might work unless you slip. those are my 2 cents.
I wouldnt bother it at all, you risk damageing it if you try to move, and even if you do move it, it will move right back to that spot. So the best advice is to just let it be.
I wouldn't mess with it unless you absolutly have to!!! For one thing they can move and it will very likely just be right back where you removed it from. Your chances of hurting this guy are pretty great if you absolutly have to remove one I'd use the ice cube trick but, don't do it unless your anem is in danger or about to cause harm to another critter.