Listen, there's no way to stop roosters from crowing. They do it at any time of day, and some even at night. If you're going to raise poultry, you have to have cock birds, and cock birds crow.
Some folks get around the noise by offering free eggs to the neighbors. After a while you really don't hear it. If you have a good relationship with your neighbors you should be fine. Be sure to check your zoning laws.
There's no such thing as a muzzle for a cock bird. They crow, and we live with it.