What wheel do you have? Both styles of horn buttons pull off the horn switch. If it is the wheel with the holes in the spokes, be careful with it. The spoke type wheel center cap is plastic melted around a set of metal fingers that grab the horn switch under the button. They will pull out of the cap and then you will need a new cap. Go slowly and then you should be fine. If it is a 70-71 wheel there are screws in the back of the spokes. One you take the spoke cover off then the cap can be pulled from the horn switch.