When someone says cut it out, it means to stop doing what one is doing.
To stop being annoying, irritating, or bothersome.
Spoken as a direct command or order.
1. Jamie stop bothering your sister. Cut it out!
2. Making jokes in front of my boss is so funny but yesterday he told me to cut it out.
3. If you’re fooling around with liquids in the garage, you’d better cut it out.
4. A: What’s that thing behind you? It’s hideous! Run!!
B: Cut it out! You’re scaring me!
back off, break off, call it quits, come to an end, desist, fail, give it up, halt, knock it off, refrain, terminate, quit