The best cat urine odor remover I've ever found is Lemon Scented Pine Sol.
I had a problem with cat urine smells when I babysat my father's cat for 3 months. I tried Vinegar, Baking Soda, Enzymes, and Febreze. None of these worked for me.
What finally eliminated stench of pee was Lemon Scented Pine Sol. Nothing else even dented that smell.
Pour undiluted Lemon Scented Pine Sol into a spritzer bottle and spray the inside of the closet with this.
Allow to dry.
Small warning: the scent of the Lemon Pine Sol will be absolutely overwhelming for a while (it actually made me woozy), but the smell dissipates. And once it does the urine smell will be gone -- not covered up, but gone.
You might have to repeat a couple of times, but this works. This is the ONLY thing I have ever found that gets rid of the smell of cat urine.
Make sure you use the Lemon Scented Pine Sol, not the regular scent.
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