The only way to destroy a demon permanently is to call down an angel when it is present and not possessing a vessel. Given how fast they move, it is almost impossible to do unless they are trapped within a ward. Invoking an angel requires knowledge of some form of the rite and a successful Lore roll. The angel will manifest in the zone the next turn and destroy any demon present.
Consecrated ground is always under the protection of an angel and any demon entering such a place will be destroyed, as above. Thus, no demon will enter such a place.
Four Blessed Things
“Allah has sent down from the heavens to the earth four blessed things: Iron, fire, water and salt.”
These four things can be used to hurt, ward against, or drive off demons. Any person who is aware of this can place a Warded aspect on a zone or make an attack against a demon. They cannot be destroyed in this manner, but taking them out will force them to flee.