Pull it from your tank, toss it on the floor, then put the pieced back into your tank where you like them.
A very simple coral to frag, but they are a difficult coral to raise in home aqauria. If you have had the specimen for some time and it shows to be healthy and strong growth then go for it.
If you just got it and it is large so it put an idea into your head about fragging it. DONT. It is very difficult to bring a damaged one back if it is a new specimen. Get familiar with it and let it grow in your tank untill you see it is healthy and happy. At least a few months to be safe.............
............then throw it down a flight of stairs and pick up the chunks. The fragging is the easy part, its the experience and long term care that is the beast with these corals.
-JMO