You have to find the nest(s). So the first thing is to see if they are digger wasps (holes in the ground, like ants) or the kind that are papery globes (like hornets make) that hang under eaves (especially in the peak), decks, branches, mailboxes even light fixtures. We've had them in all 5 places. The digger kind, you pour something down the hole. The other kind, you spray. Do your looking and your treatment in the evening when the bulk of the wasps are inside. If you spray/treat during the day, the wasps come back, can't find their nest, get screwed up, and start building a new one. Wasp/hornet spray has a very direct, powerful, thin line of spray that goes right into the hole on the bottom of the nest, vs. a general air-blown spray. Think of a hose nozzle and the difference between "shower" and "power spray".
So, slowly follow the wasps if you can to find out where they live. Wear long sleeves and a hat, and try it in the early evening when they are "heading home from work". Don't do anything - just locate. If they are digging holes, mark nearby with a stick or a down in the ground. When you identify all the locations, make a little map and then go out and do all of them at once. Wear one of those dust masks and work goggles to protect your nose/eyes. Spray fast up into the nest, and then get out of there - they will be "mad as a hornet" but you'll get most of them. After a few days to be sure they are all dead, you can knock the nest down (it may start to fall apart anyway without live wasps to repair it).
If they are way up in a high tree or in a dangerous part of the roof, hire a professional.
Good luck!