The 'boss' says to use a mixture of bleach, hot water and a little liquid dish soap. Wear a face mask so you don't breath in all the spores from the mold. You may need to give the grills a couple of washings.
If you are passing a Camping World, I think they sell replacement grills for your grill.
Tom and Katharine
'07 Winnebago Tour 40TD, 400hp Cummins
'17 Winnebago View 24V, '02 R-Vision B+
RVing for 20 years & 200,000+ miles