Cast Out Evil In My House?

I have a very stubborn evil spirit in my house. My boyfriend and I are very spiritual and we tried to cleanse the house last night and cast the spirit out. We walked around with sage and said words in our head to cast it out. However, it is still here. He is very spiritually strong and I am not so strong, but I believe if I try I can get rid of this evil. The spirit is afraid of my boyfriend. The spirit will be in one spot (we can usually sense it when we walk in the room) and when he enters the room, it leaves. It knows he's capable of getting rid of it. I don't believe in God, but I believe in a higher being in which I do not know his or her name. So, what is like a prayer or something I say as I walk through my house with sage to get rid of it?