7 Answers

Advice here :http://www.ehow.co.uk/how_6548640_cat-urine-smell-out-sofa.html

Rub Bi-Carbonate of Soda onto the area and leave for a few hours, dust off and repeat if necessary.

All excellent answers above!! I was going to say get rid of the cat..

Things You'll Need
Rags
Black light (for old stains)
Spray bottle
White vinegar
Water
15 oz. hydrogen peroxide
Baking soda
1 tbsp. liquid soap
Plastic bucket
Vacuum cleaner

Instructions
1
Soak up fresh cat urine with rags. Blot the spot rather than rubbing so the urine is not spread farther. Continue blotting until no more urine transfers from the sofa to the rags. If the urine spot is old, use a black light to locate the urine stain.

2
Fill a clean spray bottle with 1 part white vinegar and 2 parts warm water. Spray the affected area of the couch.

3
Blot the area again with a clean rag to remove the moisture from the vinegar spray. Continue blotting until no more moisture transfers from the couch to the rag.

4
Mix 15 oz. hydrogen peroxide, 2 tbsp. baking soda, and 1 tbsp. liquid soap into a plastic bucket. Stir the ingredients gently to combine. The reaction from the baking soda and peroxide will cause fizzing if stirred too briskly.

5
Dip a rag into the cleaning solution. Scrub the affected area of the couch with the solution.

6
Rinse the sofa with a rag and warm water. Blot with a rag to lift excess moisture from the sofa.

7
Sprinkle the sofa with a generous amount of baking soda to continue deodorizing the area. Let the baking soda sit overnight before vacuuming up the powder.

Read more: How to Get Cat Urine Smell Out of a Sofa | eHow.com http://www.ehow.com/how_6548640_cat-urine-smell-out-sofa.html#ixzz2OHGqpcWd

I go with the replies to dump the cat. 

Get rid of the couch and the feline.

clean sofa as above and get rid of cat.