how do you evict a person who is not on the lease?

My boyfriend and I moved into an apartment in June of this year. His mom had no where to go, and he let her come stay here with the intentions that she was going to help out. We have had to put padlocks on doors because she has been stealing things. She refuses to find a job and help out, and does nothing but sit around the house all day and mooches off of everything. The power bill is in her name but we pay it. She has also refused to watch her granddaughter which would be my boyfriends and I daughter, unless she is getting paid to do so. So what is the proper way to get this lazy MONSTER out of my house! somebody please help!