I have found that the best way to clean male plastic urinals is to use vinegar.

I rinse with a 50/50 vinegar and water solution as needed to clean and control odors.

You are in control!

Vinegar is the recommended solution by MUDS LLC for cleaning the MUDS.  It will kill most mold, bacteria, and germs because of the acidity.  It is a cheap cleaning product and is environmentally friendly.