I think it would be best to have a vet do it tbh. It's extremely painful for the bird without anesthetization
https://www.humanesociety.org/sites/default/files/docs/hsus-report-caponizing-chickens.pdf
Here we very often caponize extra cockerels of all breeds except Cornish crosses. They get large, they don't crow, they are not obnoxious and they are fetch high price in the market. I had a capon that used to take care of chicks like a hen. I allowed him to live for three and half years he schooled many batches of chicks.