If you are showing (at least in the UK) you do not dehorn Jerseys. If he has much horn then it needs cutting with a wire and then cauterising. I have done it under supervision but would not do it without expert help as an anaesthetic is injected just above the eye.
If the horn is only buds then it can be straight cauterised
I hope that you know that both Jersey and Guernsey bulls are notoriously bad tempered. Many farmers who have the herds refuse to keep a J or G bull on the place.