Just snap them off. As long as you're not using the 2-part putty, they will lift off with a bit of pressure from either your fingers or a small tool like the tip of a tweezer or prong.
Easy. I usually use my long tweezers and just rock the base back & forth a few times. They pop right off. The only time you will have a problem is if the coral has started to really attach to your rockwork.