How do I get a family member out

[Kay Rock]

Good Morning All,

I have a cousin living with me, she has been paying $500 per month for the year for a year; she does not have a lease). She moved in with one child, now she has 2, there is not enough room for her anymore. I told her not to give me money for June & July and to move out by August, she told me she is not leaving. How can I get her out? Should I give her a written notice?  What should it say? 

 Thanks in advance

Kayann.