Do I need to break off blackening pieces of stylophora?

During a recent move of my tank, a frag of stylophora broke off the main piece in my tank. The rest of the coral is very healthy, but the part near the fracture has blackened and is now populated by a tiny vermatid snail. Is it good practice to cut this failing pieces of coral off? If so, how is this done?

 

If it's visually displeasing I would just tank a pair of bone cutters and snip it off, any clean snipping tool or pliers will work. If the removed area is viable you can just give it a quick dip in a diluted iodine solution and start a new colony. Fragging is quite common.