So, there are 2 types of exorcisms, minor and major. Any RC priest can do a rite of minor exorcism, which is more of blessing, on objects, locations, and people. the priest walks around, says some prayers, flicks some holy water, and burns a little incense, and its supposed to drive out minor demons and problems.
The rite of major exorcism, or the Roman ritual, is the big gun. They need permission from the Vatican, who will demand proof of a major demonic possession before approving it. it has to be carried out by specially trained exorcists, who are chosen by their bishop for their faith and piety, and are apprenticed to current exorcists for years. It's considered "spiritual warfare" and is deadly serious.