As a Latter-day Saint and one who posesses the authority of the priesthood I have cast out evil spirits on a few occasions.
I have done it through a priesthood blessing, placing my hands upon the person's head, stating my authority and casting the unclean spirit to come out in the name of Jesus Christ.
I also have been warned by the Spirit to stay away from an individual, I raised my arm to the square, stated my authority and cast the spirit out in the name of Jesus Christ.
Each time the spirit(s) have departed. With one sister, they continue to come back and it's because of the choices she makes.
Everyone is worked upon by evil spirits. We all should want to live righteously so that when we wake up in the morning, the devil and his angels will say, "Oh no, he's awake!".
M