Do not use heat on the coupling/shaft!!
You will ruin the heat treatment.
Support it with a jack or piece of metal on concrete and whack the pin punch with a B.F.hammer, sometimes a person can hold the pin punch with a pair of vice grips if they are afraid of hitting their hand/fingers.
If the coiled pin is mushroomed, hit it from the other end or grind it flush.
You will not get it out if it has a mushroomed head.
As mentioned an air hammer works well,
but still
solidly support the shaft, as it makes
the pin come out easier.