How do I evict a family member that does not pay rent and was only to be staying with us til October?

My housemate(boyfriend) had his 27yr old son and girlfriend move in as a temporary arrangement til october not paying rent so that they could save up due to a new baby born in August. They refuse to follow any rules, including locking the door, cleaning up their mess, etc. After a confrontation last week, I told them they had two weeks to get out of my house. The house is in my name only. They are refusing to leave, can I get the cops involved to escort them out? Any advice is helpful. Thank you.