How do I frag a sun coral?

[GrimReefer]

How do I frag a sun coral?

When I first got my sun coral 2 weeks ago, I placed it on my sandbed. Didn't realize a few polyps were burried around the back. The flesh from those polyps died and sloughed off, but it seems to be continuing to errode into the healthy colony. I placed it on the rockwork in good flow, and it's been opening up for feeding nightly.