The religious or spiritual practice of evicting demons from a person is called exorcism.
The word describes a ritual intended to drive out demons, evil spirits, or other malevolent supernatural entities from someone believed to be possessed. Depending on the tradition, an exorcism may involve prayers, commands, sacred words, gestures, holy water, religious symbols, music, or other ritual actions.
Exorcism is not limited to one religion. Forms of spirit-removal or spirit-banishing appear in Christianity, Judaism, Islam, Buddhism, and other religious or cultural traditions. In Christianity, the person conducting the rite is commonly called an exorcist. In the Catholic Church, formal exorcisms are performed by priests with authorization from church authorities, and suspected possession is meant to be distinguished from medical or psychological conditions.
The practice has ancient roots, while modern popular culture has especially associated it with horror films such as The Exorcist. In ordinary usage, “exorcism” specifically refers to expelling a spirit; “exorcist” refers to the person who performs the rite.