Getting rid of mold?

[Paleosuchus]

I did a search on mold and found only one post on this but it did not say how to get rid of it. The cage is wood with a nice coat of polyurethane. I was careless and got the cypress mulch way to wet. I have tried scrubbing with warm water and soap but nothing. I was told to use diluted bleach but not sure what percentage it needs to be with water. Thanks for any help, Jason