Have you tried this? https://www.hometalk.com/3369992/destroy-anthills-with-an-orange
Ants are necessary but not when they become invasive. They need to have the colony destroyed and there is an easy way to do it that is SAFE, inexpensive, and best of all it WORKS. https://www.hometalk.com/36651130/ants-safe-and-effective-cure
We had a fairly large anthill in our backyard for almost 30 years!! Could not get rid of it no matter what we tried. The only thing we were killing was the grass! Finally picked up a can of Wilson One Shot Jet Foam ant killer. Using a quarter inch diameter bamboo stake, I had my husband poke holes as deep as he could (probably ten inches or so)and a couple of inches apart. The One Shot has a tube you attach to the nozzle and my husband filled each hole with foam and after all those years we destroyed the entire colony. That was last summer and the grass has filled back in and you would never know where the ant hill was. Highly recommend
the Wilson One Shot. What ever you try, good luck!