How would you remove broken bridge pins from an acoustic without the main soundhole?
If the knob on top has gone, then use a drill bit slightly smaller than the end taper of the pin - use another pin as a guide. Drill slowly, perpendicular to the bridge, and most of the pin will disappear. Use a slightly larger diameter bit to take out most of what's left. The remains will then be easy to dig out gently with a small screwdriver. Do not use a bit any larger than the original hole size - measured by inserting a bit into another bridge pin hole.