Mr C Braxmaier,
I am fairly well convinced that the shaft is held on with the round bush at the base of the square drive. It looks like you've found the taper pin that is holding it on.
As was noted that pin will only come out 1 way....Can you get a good photograph of the ends of the pins?
I may be able to advise if the damage isn't too bad.
Once that pin is out, you will arrive at two choices....the bush slides right off? or The bush is threaded onto the shaft and will need to be unscrewed.....I'm betting on the later.
When banging out a taper pin, make sure your driving from the small side, and the other end has somewhere to go....
Dave