oh yeah, its most definitely inhumane, i would never do it. but it can be done. My roosters seem to find crowing one of the funnest activities they can think of, i just wish they didn't have so much "fun" at 4 am... but it would be terrible to take that away, i'v seen videos of "de-crowed" roosters pointing their heads up and trying to crow, its kinda sad.
Surgically de-crowing a rooster is like de-barking a dog. Cruel, useless. Now, there are people I've heard who ended up with a rooster that had a "crowless" gene. As in, they never crowed. Don't know much about it though.