How do I get rid of flying gnats?

Put apple cider vinegar and a smidgen of dish soap in a small bowl. Works wonders. Make sure it is apple cedar vinegar

The vinegar trap in the covered glass jar a cup has always worked for me.

Per link below

“Get Rid of Fruitflies with a Homemade Fruit Fly Trap. Pour just enough cider vinegar to cover the bottom of the jar. Add a drop of dish soap (it will break the surface tension of the vinegar so the fruit flies can't just sit atop the liquid). Now, cover the jar with plastic wrap and poke a few holes in the top.”

https://www.apartmenttherapy.com/homemade-fruit-fly-trap-123615

Here is a fruit fly trap that works well for me https://www.homeroad.net/2015/10/a-fruit-fly-trap-that-works.html

First you should find the nest. They might be in your sink. I called an exterminator. They were all over my kitchen & dining room. I got some free advice.

I had a terrible gnat problem and the vinegar traps worked perfectly! Simply place a few tablespoons of apple cider vinegar or white vinegar, a few drops of dish soap, and a tablespoon of sugar in a bowl and stir. Set your bowl in an area where gnats are prevalent, such as your kitchen or bathroom. This took care of my problem in just a couple of days!