The concept of "cut it out" can be shown in a couple of ways.
You could use a one handed version of FINISH:
This
version of FINISH means "Knock it off!"
You could sign "Don't!"
Or you could sign STOP!
The sign for "stop" is
made by extending your left hand, palm upward. Sharply bring your open right hand down to your left
palm at a right
angle.
STOP: