My nephew on the bathroom wall and floor cupboards and urinated and I have tried everything to get the urine?

Sounds to me like it happened more than once, and the urine has soaked into the materials. All you need to do is seal the areas with an odor blocking primer and repaint.

If you have peel and stick tiles on the floor the enzyme cleaner will work, but you need to seal the walls and baseboards before you’ll know if it has gotten into the seams in the floor.

If you don’t want to paint, just seal any “wood appearing” items with a couple of coats of poly, but make sure you seal the entire surface: Back, bottom, etc. Anywhere the urine has gone the smell will remain without sealant.