I once used a beautiful tool similar to a bicycle chain tool to push out the pin. It did not work.
I wound up using my dremel with a thin diamond coated cut off wheel to cut the pin on both sides.
Similar to this:
After This I was able to remove the hardware from the glass and use a hammer and punch to remove the 3 sections of pin that remained.
I now just use regular cotter pins, and can easily remove any of the 4 pop out windows in under a minute.
Certainly makes tinting those windows much easier too.