I find the naming a little inconsistent and somehow liked the name sharp better. At least I believe the command was named ‘sharp’ a while ago.
Using the keyboard, typing cre ist enough to get the crease command.
shar would be enough to get the sharp command, which could be named _SharpenSubD or simply _Sharpen.
I know I can create my own alias but overall I think the command names could be improved.
Instead of having three buttons in the toolbar, two would be enough.
One button with the left mouse command set to _Crease, RMB set to _RemoveCrease.
_Sharp or _Sharpen could also have _RemoveCrease as RMB option.