Fotzlid

You need to find the nest first. It could be underground if there is nothing obvious hanging anywhere.
They will keep coming back so long as the nest is intact. Protecting the queen and all that or however wasps divide labor.
A healthy blast of high pressure water will destroy their paper mache fortress and force them to seek refuge somewhere else. Can be done from a safe distance and you can pick off any that fly in your direction. A strong shower type spray can be effective in keeping them at bay.
Just be sure to knock the entire thing down. If its just damaged, they will rebuild it almost overnight.
If you have a truly monstrous nest, you'll have to hire someone to get rid of it unless you want to buy a bee suit.