Remove the small cotter pin from the retainer pin. Remove the retainer pin and drive the main pin out from the side. The only thing you have to be careful is not to damage the zirc that is recessed in the main pin, other than that, it's a solid piece without anything else to worry about. Then remove the other two pins for the loader frame, but they only have larger cotter pins keeping the main pins in place. Drive them out as well.
When reassembling, it's easier to temorarily install all main pins, without worrying about hole alignment for the cotter pins. Have somebody watch the holes as you turn the bucket and eventually the holes will align themselves as long as you have them at the right depth. A small alignment tool will help finish the job at this point.