It would all be simple, right? The problem is that the story heroes of the campaign (i.e., Anton, Anastasia, etc.) cannot be deleted. At least, not in the game itself. And this is a serious flaw – for example, one person completed all the campaigns with the heroes of Tears. Then they will not be able to play the bonus mission of Blood. Why the developers did it this way is unclear.
In general, if a campaign is completed with a non-story hero, then that hero can be deleted and the campaign can be replayed; in Dynasty, the story hero will appear as completed. But if you play the story campaign again, it won't change. However, there is one trick that I haven't checked yet. You can either click on the crossed swords on the map or use the "Start Over" button. Maybe then it will change...