Wash it off good,let dry and give the plywood two coats of Kilz oil base, not water based.
After my MIL passed away, we had to sell her condo.She kept a little dog there. Inside all day long when she was out and about. Sh eha dthos ebig pet mats,but the dog never used them, we had to pull all the carpeting and that urine smell was soaked into the plywood flooring.Two coats of Kilz sealed it up.No smell.
You might even try some of that solution they sell to get rid of skunk smell when you wash it
