"Knock it off" is a phrase commonly used to order someone to stop doing something. However, there are several other synonyms for this phrase that can be used instead. For instance, one could say "cut it out" or "cease and desist". Additionally, one can use "quit it" or simply say "stop" to get the point across. "Enough" or "that's sufficient" are also phrases that can be used to stop someone's behavior. These synonyms convey the same message but may vary in tone and level of seriousness. Whatever the occasion, using such phrases or its synonyms are a polite yet firm way to get someone to stop a certain action.