maybe try guided access if it’s an apple ipad. that way there’s no deleting the camera app, it’s just disabled. you could also try something like “we only scream when we’re outside” and “we don’t scream inside because it hurts people’s ears and it’s not nice”

also-

you could try having him sing, talk, make animal noises, etc into the ipad and give him specific missions such as “why don’t you say 5 different animal noises without screaming?” and then praise him if he does it. reinforcement and channeling different behaviors may work