Looks like Contact Dermatitis from being on wet ground, exposure to ammonia in droppings/debris, etc.
Do you have photos of the housing/coop/run where he lives?
This is pretty advanced, so it may be infected too. If you have vet care, that would be best.
If I were going to try to treat this, I'd used Tricide Neo. This
Post tells you how to use it, this is
where to buy it. It's extremely important that your rooster is kept on clean, dry bedding. And treatment is kept up with daily.
This is what the very early stages of Contact Dermatitis looks like.
https://www.backyardchickens.com/ar...contact-dermatitis-foot-pad-dermatitis.78413/