Dispatching a chicken is really not hard. It isn't easy to do (mentally), but it isn't complicated. I really do believe that every chicken owner should know how to do it. Even if it isn't a rooster, it could be a hen that is mamed by a predator, or has an illness that can't be cured. It will need to be done to one of your chickens at some point, even if you don't want it to. It is part of having chickens. You should be able to do it.
If you check with your local university extension or the permaculture guild, they often have workshops on butchering meat birds. I attended one locally. It gave me a lot of confidence in my ability to humanely and quickly dispatch a bird. If you live near me, I will be butchering chickens the week before Thanksgiving. You can come participate. Bring your unwanted roosters and i will help you dispatch them.
I don't mean to get on everyone's case about this, but I see roosters on CL all the time. Then to see all those roosters on that show. 102 is a whole lot of roosters. And that is just ONE operation. Rufus has told us about the "other thing" that these unwanted birds are often used for. I just don't want to contribute to either situation and I would rather take care of the situation myself than turn a blind eye. I know none of you wants to contribute to the madness, either. I am certainly not suggesting you do.
Let me know if I can help.
What I do:
zip tie legs together above knees
put chicken upside down in a cone (traffic cone, or I have a cone shaped cage made from chicken wire - super simple, just holds birds still)
just below the ear lobe is a soft spot where that main vein is. Slice it with a very sharp knife. They don't fuss, just bleed out quickly. It takes a minute or so. Very humane and quick.
For butchering instructions, there is a great sticky in the meat bird section.