You wait till after dusk! They go to bed, usually have a sentry posted at the mouth of the nest. I had DH go with me for back up. I dressed in appropriate clothing for the attack. Intent was to scrape the nest into a waiting bucket of hot soapy water with a spatula. Unfortunately, the nest wouldn't scrape! So, in a bit of hurried frustration, I just plucked it off it's attachment with my rubber gloved hand, and dumped it into the soapy water, giving it a good squeeze as I did so. I then found the sentry on the ground, scooped her into the soapy bath, and the job was done.
This morning, I inspected, and found that the nest was FULL of fat larvae. The started nest was loaded up with eggs.
FYI, I was wearing flannel shirt under a rain coat, and an insect net over my head, pants pulled down over rubber boots.