Greys and Reds don’t live in holes in the ground, they are tree squirrels. You might want to buy a .177 pellet gun, they will take care of the problem. If you don’t want to do it, get someone else, I am sure someone will volunteer.
Caution!!
Tree squirrels are considered game animals in most states, there is a bag limit as well as a season. Most states don’t allow air rifles to hunt game animals.
A pellet gun would work but I prefer something that goes boom - or at least bang.
But at the rate they are chewing up plastic resin yard furniture & stuff they might die anyway. Funny, we never had the problem with them chewing up that kind of stuff til this year, and the neighbors are seeing it to. They are eating it or at least carrying it off - there's a huge hole in the trash can and not near enough chips on the ground to make the hole.