Natural cat urine cleaning. After using two different types of cat-pee cleaners that did nothing for a trouble spot on the carpet, we did this and the odor is gone and the cat has stopped peeing there! It's quite a bit of work, but was totally worth it.
My go-to. There's no store bought spray I've ever used that adds up to Remove Cat Urine and Dog Urine from carpet quite like this one. Mix 1 part water, and 3 parts vinegar. Spray. Let it soak for 30 minutes. Mix 1 cup of hydrogen peroxide, 2 teaspoons of baking soda, and a squirt of dish-washing liquid. Shake it well. Spray, and let it soak/dry. Adjustments can be made for the measurements, to your liking.