Building A Rock Retaining Wall I Have A Rock Retaining Wall With Wasps All Over It. How Do I Find And Remove The Nest I Know They Built?

I have a rock retaining wall with wasps all over it. How do I find and remove the nest I know they built? - building a rock retaining wall

I have two apple trees next to where they are, I'm sure what the first one. Even wasps seem typical, but Sting like them! Help! Thank you!