Problems with extra people in apt

have tenants without lease. were told prior to moving in (No extra people staying in apt) I told them once in a while but not every weekend or every other weekend. I have had to tell them repeatedly and send them notes over and over as they disregard what I have told them. They have his mother come to stay every weekend(Her Mom Lives with them and2 children. I have had enough of their sneaky behaviot(they had their brother staying with them without informing me0 I confronted them about the situation and told them to leave in 30 days.I told them the extra mother could not stay during the 30 days and the male tenantsaid she was staying take him to court. When i give written notice, can i say i will have the police remove her if she stays on week ends? Do they also pay me rent for the 30 days?