MYO Urine remover from drywall

I have a bathroom with the potty sitting very close to the wall. I am not sure if the boys cant aim, or if the ‘stuff’ coming out of the potty while flushing, but I have a horrid urine smell in the drywall. I was wondering if anyone has any idea how to get rid of the smell.

I have tried spic and span, TSP, and soft scrub. Any one of any other ideas?

Thank you in advance for any suggestions you might have.