Buttonectomy.
 

I've been nipping the central buttons off my caps for years. Found this little video which demonstrates the surgical procedure.

The video was obviously carefully designed to take into account the mechanical aptitude of the average aeroplane pilot. Some should ideally seek help from a qualified mechanic to assist, to avoid accidents.

The Health and Safety reps would probably wish to point out that insufficient protective clothing was worn by the operative and that warning signs should have been placed outside a cordoned off area whilst snipping bits off with a nasty, pointy tool was in progress.