In many traditions of Paganism and Wicca, banishing is done to get rid of negative energy, unwanted energy, or even people who causing problems in our lives. While some traditions frown upon banishing as manipulative magic on the theory that it impacts the free will of another, if your tradition has no prohibitions against such things, then there’s no reason you can’t do a banishing to get rid of negativity.
There are a number of different methods to accomplishing a successful banishing. Which one you choose will vary, depending on how comfortable you are with the different techniques, and what you’re trying to achieve.
If you’re trying to get rid of an unwanted spirit, one of the most effective methods is to simply give it its marching orders. Be firm and blunt, and say something along the lines of, “This is not the place for you, and it’s time for you to leave.” You may wish to offer a blessing or well-wishes if it makes you feel better about things, and say, “It is time for you to move on, and we wish you the best in your new place.” Frequently, this will do the trick and your problems will be solved.