Human urine is one of the more difficult substances to completely remove from an absorbent object, because it contains salts that seep deep into an object. Unlike the rest of the urine, the salts do not evaporate and leave the area. Instead, they stay and attract moisture. The extra moisture makes a great environment for mold, viruses and bacteria. The mold and bacteria are what actually causes the smell. A disturbing stench is by far not the only concern when dealing with urine.
Clean the uppermost surface of the contaminated object with upholstery cleaner and a scrub brush. If the object that has been urinated on is not absorbent, this may be the only step. Make sure to get the bristles of the scrub brush as deeply into the object as possible.
Clean the back or under side of the contaminated object. Different objects require different methods to get to their inner or back area. If you are cleaning carpet, pull up the carpet and scrub the back side of it. Then thoroughly clean the pad beneath the carpet on both sides. If the contaminated object is a piece of upholstered furniture, you may have to disassemble the object. Make sure to get the bristles of the scrub brush into every part of the inner upholstery.
Allow the upholstery (if that is what you are working on) to dry and then reassemble the object. If the urine smell still persists, move on to the next step.
Throw the contaminated object away. This may not be a desirable option in many cases. Replacing furniture or carpeting can be very expensive, not to mention a lot of hassle. However, having objects that are contaminated with human urine in a living environment can be very dangerous. It is better to remove the contaminated object from the environment than risk illness. Sometimes, the trash is the only option.