This is good advice, however be sure to also change the locks if your husband has a key.Thank you for answering my question.
This woman does not work at the salon? Does her hair need frequent touch-ups or cuts or whatever? Doesn't really matter.
Just call the police and, because she has been warned not to trespass, if she trespasses (if your spouse has not given her permission to be at the salon and he has permission to be there), the police can arrest her.
You can also fire your husband, if he is an occasional worker at your salon, you own the salon, and you do not want either of them in your salon.