How do I legally get rid of unwanted "guest" in my house?

Question Details: I own a house. I moved out of my house and in with my boyfriend. I let my brother and his family move into MY house- the verbal agreement was they weren't going to pay me rent for a year so they could get back on their feet. All they paid was some utilities- the utilities are in my name and my brother's name. They have recently split with no chance of getting back together. My brother moved out and she is still there with the kids. He didn't have the heart to make her leave. I want her out of MY house. I am willing to give 30 day notice due to kids. What can I do? We live in PA. Important Notice