When it's time for new leases, put a specific clause in there to address situations such as this, and attach a dollar value to it. If they violate it, they get a warning, second time, warning and fine as stated in the lease. 3rd time and it's an eviction. "3 strikes (maximum) and you are OUT"! is a real good motto in management, and landlording.
Don't let your tenants "pull dominance" (like dogs do) on you like this, because if you let it slide, some will escalate to levels you won't believe.