A good way to kill the smell of cat urine is by use of vinegar and water.
You can spray the vinegar and water onto the cat urine and allow it to sit and then clean it off with an upholstery cleaner.
I've used vinegar on carpets and upholstery to clean cat urine up with an upholstery cleaner and it works great.
You can also go to Walmart or pet stores and buy some cat urine odor neutralizer that works even better than the vinegar but if all you have is some vinegar that will work as well.
Make sure to keep the are clean where the cat urinated so they don't smell the scent again and pee there in the same spot.
If your cat is peeing outside the litter box make sure the litter box is clean and always redirect the cat to the litter box if you catch them peeing outside the litter box.
Keeping the litter box clean also helps to keep the smell down in your house as well.
Vinegar is very acidic which helps to neutralize the urine odor.
Mix white vinegar or apple cider vinegar in water to dilute it (usually 1:1 ratio) and spray the solution on any fabric or floor