making a pact with a demon allows you the lifestyle perks to do it

Every major supernatural perk tree has at least some skills that deal with wraiths. I haven't played the current build of the mod yet, but basically, look for the 'Banish' ability. Also you used to be able to turn them into artifacts wholesale IIRC but I am not sure if that works the same anymore.

Personally I keep them around just to have a more supernatural court/realm. Later in the game when you have a high opinion bonus it's enough for other supernaturals to like you somewhat, meaning they won't be constantly trying to kill you or whatever.