Many PEOPLE clip their birds wings, but birds don't clip their own feathers. Old feathers fall out then new feathers grow in to replace them. It's not uncommon for captive/pet birds to pluck their feathers out leaving bald areas; is this what he is doing?
feather destruction can be a complicated issue but the first thing to look at is health when was his last vet visit w/ gram stain. 2nd look at diet artificial foods such as pellets or fortified seed blends can have adverse affects on some birds just like people.
I wouldn't understand why a macaw would "clip" it's own wings and destroy its own flight ability.
Are you sure the mac is not PLUCKING out his own feathers ... if this were the case he'd wouldn't just be focusing on the flight feathers he'd be plucking out all of them.
My African Grey did this for the first 4 years of his life. but only onhis left side. It was becaus he was clipped before he fledged but they only clipped one wing. it was also a bad clip. Any way he no longer barbers his wings what I did was take him into the vet and got both wings clipped to match each other and after that he stopped barbering he still can't fly very well but he is fully flighted He never learned to fly as a baby and now he's 6 years old and can only fly short distances. I don't know if this would work for you but if he was clipped properly and evened out his flights he may let them grow back in.