If he contributes to the household bills, you need to serve him with a notice to vacate and follow up with a formal eviction. Here is a link that can help you with the format of the vacate notice:
Landlord's Notice to Vacate - Free Legal Form
with all legal issues, it is best to seek the advice of an attorney.
If he does not contribute any monies to the household at all, you can change the locks. But, you are legally responsible for ensuring that he receives all of his belongings.