I work on a golf course and take care of all the wasp nests. I've only been stung twice all summer and that was just from random walking around and not seeing them; I've not been stung while actually taking a nest out.
You can't see the nest, so that means there probably isn't one right there. You've got something out there they like... some spilled juice or pop or something maybe?
If you can see the nest you need to determine if it's in the ground or in a tree. If it's in a tree it's super simple. I put on full rain gear, heavy gloves, and a mask. I make sure that the wasps have absolutely no way to get in and sting me. Then I take 2 doubled up garbage bags put them around the nest, clip it off the branch, tie it off, then walk away. Shake it up some to listen to them buzz like mad
If it's in the ground it's a little tougher. Again, I gear up, then dig the biznatches up with a shovel, smash the nest, then put it in a garbage bag. Fill the hole in, walk away.
The spray is good stuff, but you have to get them early in the morning or late at night (like 11 pm to 5 am times). Spray the hole in the nest or ground. Make sure to get it good, then leave for a few hours. Most times it kills a lot of them but it doesn't get them all. What's more, is if you just leave it like that, more often than not they survivors will rebuild the nest again. The only good way to take them out is the garbage bag routine.
If you have a pole pruner, I've discovered from experience that wasps are dumb. You can be whacking at the branch or nest itself with a pole pruner or stick and the wasps will only attack the pole up to 4-5 feet away from the nest. They'll ignore you completely if you're 8-10 feet away. Weird I know, but I've been able to cut a lot of nests down wearing just shorts and a t-shirt with a pole pruner that way. Of course when it came down towards me I ran like a bat out of hell
