They're swaged in place.
If you clean/examine the top and bottom of each hinge where the hinge pin is fitted, you'll likely see what looks like 2 or 3? chisel type depressions which lock the hinge pin in place. Either the top or bottom swaging needs to be removed e.g by grinding off 2-3 mm.
The big difficulty is getting access, both to grind and then drive the pin out (which may be rusted (frozen) in place). If you can't get access for a hammer + drift, you might be able to use a flat bar with a pin welded on one end to contact the hinge pin and strike the bar at a point back from the end. Might also be possible to adapt a balljoint/steering track rod joint separator tool to push out the hinge pin. As you have an air hammer, perhaps you have already have a suitable adaptor to use with this?
The hinge pin is a constant diameter but one end has 2 or 3 slightly raised lines (like you'd do with a chisel) to stop it rotating in the hinge body.
Bear in mind that the centre part of the hinge (iirc, the part that is screwed to the A pillar) is what normally pivots on the hinge pin and the bore of this can wear also, so replacing only the pin might not be a complete success. The pin is a fairly hard material and in my experience doesn't wear much but the hinge flap does. I don't know if drilling the pin out would be possible.
One trick I've used, is to heat to red hot, the part of the hinge that pivots on the hinge pin and persuade it with a hammer to close down on the pin thereby reducing the free play. You could also try cutting a narrow (1mm?) slot lengthways down the worn part of the hinge centre section, heat to red hot, squeeze it to fit the pin closely, then weld it shut. Both of these are of course 'bodges' :yuck:, but sometimes save the day in the absence of being able to bore out, fit oversize pins or bushes etc.
Be careful if hammering on these hinges, I've seen a couple of examples where the pin sheared just inside the bottom part of the hinge and then you're in for a whole new world of aggravation. Suggest you get someone to try lifting the door while you examine what's happening at the hinges.
Iirc, the door side of the hinge is welded in place and very difficult to remove, unless you remove either the door skin or part of the door frame. I've never seen these hinges, or indeed the hinge pins, available separately, (they come with the door), so any replacement is likely going to have to be a hinge salvaged from another door. (did I mention 'aggravation'....)
I have seen the pin replaced by a bolt/socket head cap screw and nut/split pin.
Al.