It's not easy removing urine stains or smell from fabric, including upholstered furniture. You may want to hire a carpet or upholstery-cleaning company, but tell them first what you need,
to see if they think they can help. This is a more expensive route, and it may cost almost as much to get a new chair.
Some people have found success with products for pet urine, found in any pet store. I've also heard that rubbing alcohol may work. Dampen the stain with rubbing alcohol then blot it up with a dry rag. If you do an on-line search with "cleaning urine stains" you'll find all kinds of information. This is a common problem!
I also strongly encourage you to give some thought to why this is happening. Incontinence is NOT normal. It could signify a bigger problem. You didn't mention who is causing the stains, but this person should be checked out by a doctor. Medications may be to blame (diuretics for heart problems or high blood pressure can make people urinate more). Also, a urinary tract infection should be ruled out.
There are several ways to treat incontinence. Some medications may reduce or even eliminate the problem. Behavioral interventions may work, where people with incontinence are taught to toilet regularly, before feeling the urge. You should also limit fluids before bedtime, as this can lessen the amount of urine made at night. Also, caffeine (in sodas, tea, coffee) can make urgency worse, so try to limit these kinds of fluids.
Finally, take steps to protect the furniture. Many kinds of personal incontinence pads are available in the store. They can be expensive, but helpful in reducing embarrassing accidents. There are pads, panty liners, and diapers --- made for men and women. You can buy these on the internet, or in most regular drug stores. You can also get waterproof mattress pads.