Sorry but the only answer I have ever known to work is to clean it.
Unfortunately men splash when they use urinals. You need to clean the panels, walls, pipes and floors in the surrounding areas. If not done properly then it stinks to high heaven.
It does work, I have done it.
Use a good quality washroom cleaner and for the first couple of times and every now and again use a product such as Prochem's Urine Neutraliser.
If that lot doesn't work then its either soaked into a pourous floor, under inaccessible areas or its the plumbing.
Hope this helps,
John