There are mods but you can also just go around the world map in devmode and destroy all of their settlements and it'll be mostly the same if they're a normal type.

Dev mode destroy all but the last settlement. Then send a dev mode instant caravan to the last one to attack it, wipe out the defenders using bomb or force flee or whatever tool you want, this will defeat the faction and they will stop sending raids or caravans. You will get some free rep with all other factions, you can use the set rep tool to remove that if you want IIRC. If you use dev mode to destroy the last location on the world map that doesn't trigger their defeat in my testing, so I believe you have to actually attack it to make it count.