You need to file either an eviction or an ejectment action in court, depending on if they meet the definition of tenants or not, I.e., if they are paying rent or not.
You should consult a landlord/tenant lawyer in your area.
This communication is not intended to create an attorney/client relationship. It is always recommended you consult an attorney in person to discuss your case. The Law Offices of Stage & Associates practices state-wide and represents homeowners and community associations. Please visit our website at www.stagelaw.com.