Best Doggie Face Cleaner?

tinamarie1974 thought this was worth mentioning said

I think you guys all know that Charlie has a white beard. What you don’t know is this boy plays hard in the yard!

His beard currently has a green tinge (grass stains) I have scrubbed it with a few different things to no avail.

Wanted to see if any of you have experience with a white face cleaner for dogs. Appreciate the feedback! Thanks