There is no 100% reliable method to stop a chicken from flying.
Probably the best way would be to dislocate it's wings and take them off! But then you are faced with the problem that the bird could jump, so now you are going to have to remove it's legs to!
But obviously this would be drastic and both cruel and very painful for your bird...
The next best and most reliable method which is used by many of my local farms/breeders is (as I have already suggested) clipping the flight feathers on just ONE wing as much as you can BEFORE it bleeds. This makes flight "almost" impossible as the wings are uneven.
Clipping both wings will not make flight uneven, the bird will just flap harder to compensate and still be able to fly!
Probably the best way would be to dislocate it's wings and take them off! But then you are faced with the problem that the bird could jump, so now you are going to have to remove it's legs to!
But obviously this would be drastic and both cruel and very painful for your bird...
The next best and most reliable method which is used by many of my local farms/breeders is (as I have already suggested) clipping the flight feathers on just ONE wing as much as you can BEFORE it bleeds. This makes flight "almost" impossible as the wings are uneven.
Clipping both wings will not make flight uneven, the bird will just flap harder to compensate and still be able to fly!