How do I remove urine stains from my garage concrete floor?

Lowes carries a product called Urine and Stain Remover. Home Depot has a similar one.

Both of these contain chemicals though. I prefer to use just water and get it as soon as possible. If that isn't possible, I use my favorite Oxy clean laundry detergent works well. Still a chemical, but not as harsh as some of the others.

I would first try 2 parts hot water and 1 part vinegar in a bucket with a mop, soak it into the area that smells and follow with sprinkling of baking soda. The baking soda might bubble up a little from the vinegar. Let it sit for a 30 minutes and rinse it all with hot water. Baking soda is good for getting rid of smells.

I'd try CLR, it's awesome

While the above suggestions will help remove very new issues on the surface anything that has soaked into the concrete will need a multiple step solution due to the Utica-acid crystals that form and an enzyme cleaner is an absolute must because the crystals are not water soluble. Use this website for step by step instructions and some recommended products. https://homerepairgeek.com/home-flooring/remove-pet-urine-off-concrete.html

I also recommend Urine-erase or Odorzyme for enzyme cleaners, they can be found here.

https://bedwettingstore.com/stain-removers.html

The important thing to remember is you need to use an amount of enzyme cleaner equal to the amount of urine so don’t be skimpy.