Here's a post that might help - https://www.littlehouseonthecorner.com/cleaning-smelly-floorboards-smell-of-urine/
Nilodor neutralizes pet odors quite well. Getting the stains out depends on the material it is made of.
I moved into a house where a cat was trapped and had used the living room carpeting as it's litter box. I tore out the carpeting and scrubbed the floor with ammonia to get the smell out. I'd try scrubbing a spot of the paneling that wouldn't be obvious just in case the ammonia would be damaging to the paneling. If it isn't damaging i'd scrub away. I spent at least 2 hours scrubbing the floor to get rid of the odor.
Even with cleaning (I prefer white vinegar), you may need to seal the panel or replace it.
Sorry for chiming in a bit late to the discussion, but I really feel like I need to add my 2 cents.
Cats don't just pee on floors and beds because they're in pain - could be a multitude of other reasons! Most common is that male cats feel the need to mark their territory.
As for myself, I finally found something that works for the cat pee smell in my home! A herbal mixture of sorts! I now recommend it to everyone because it works so freakin' well and we save SOO much money!
You should definitely check it out, we don't even buy Odorban and the likes any longer :)
What a relief to finally have gotten rid of the horrible cat pee smell, and for a decent price as well.
One of my 2 cats (both neutered males) had taken to painting all of my walls, furniture, and anything else he could reach. I was horrified when I got a UV light. He never did that in all of the 9 years I've had him and didn't when I got him a buddy (they love each other and did so right away) but when a strange black cat started showing up outside both of my cats went nuts and the older one (9) started his wall painting, as well as the curtains out in the kitty room. I couldn't keep up with it.
My cats are indoor cats so it's not like the stray is actually going to get in here but they both hate him (and he is weird...my neighbor's cats hate him too). I've tried cleaning with a pet urine enzyme and then spraying some "No More Spraying" but that hasn't worked.
He's a sneaky little bugger too; he waits until he thinks I'm not looking and then does it. He's learned that the minute I see him backing his butt up to something he gets yelled at. It wasn't until I found "Cat Spraying No More" that I was able to finally get rid of this tiresome behavior. Now my house doesn't smell like a litter box anymore :)
To be honest, I don't know too much more about it so I did a quick Google search and here's a description of the spray with a long review as well.
No I have not been paid for this post nor do I make any commissions off of it. I really just want to help you guys out. I hope you don't mind.
I'm based in Sweden, by the way, so you should be able to get it too.
Good luck with the odor! It really lowers your quality of life, doesn't it?