It's on the front of his leg where his feathers start.Where is that located on the leg? Front/back?
More photos may be helpful.
If vet care is not an option, then I would clean it out with Chlorhexidine (Hibiclens), flushing it really well. Pack the wound with triple antibiotic ointment.
If he's not picking at it, then leave it uncovered. Check the wound at least once a day, clean/flush and apply your ointment.
Not sure the cause of the wound. It may be beneficial to administer an antibiotic. Do you have anything on hand?