How do I kill yellow jacket nests?

Jo Ann...I would get a spray especially for them at Ace or Farmers Coop.

https://www.amazon.com/Raid-Hornet-Yellow-Jackets-Aerosol/dp/B01KU5U180/ref=sr_1_12_sspa?keywords=kill+yellow+jackets&qid=1558287451&s=gateway&sr=8-12-spons&psc=1

I've used a spray like this one, so I could stand back, with a clear escape plan to get back into the house incase they swarmed, which they really didn't, but I was prepared.

Just be aware that the sprays will kill plants too. when it drips off the nest, be aware of what is below it.

Kill them at night that way they’re all in the Nast plus they won’t come out after you. they can’t see in The dark so they won’t even come out of their nest unless you Break Open The nesti

The cans of instant kill spray that you buy at the store I’ve sprayed it directly on Numerous types of plants without any harm to the plants. Make sure to read the label on whatever you’re using always read the label when you spray a chemical