The method of exorcism most useful against demons is to recite an incantation which is long and detailed, which is heavily charged with energy that comes not from the mind, but from the glory of the gods. This kind of exorcism is often used by religions such as Christianity, because you do not need to possess magical gifts to be able to use energy that comes from the gods. This method is a good one for two reasons.
First, it uses a force so pure that when the demon leaves the body of the victim, it will already be so immersed in this energy that it will be annihilated. Secondly, you do not need to adapt the incantation according to the identity or strength of the evil spirit, since the power of the gods still exceed the power of the demon.
Here is a prayer of exorcism which became particularly strong after being used in different variations for centuries against many demons. It is in Latin and is the root of the pagan rites of exorcism used by Christians