this is a recurring issue which we face in our Adobe Campaign Classic instance. Whenever a user or admin leaves our organization, as per the standard protocol we have to restrict all access of that user. This applies to ACC access as well. Hence we are required to delete ACC account of that user. But in case of ACC we are unable to do that. During the tenure of any ACC user or admin there are a couple of workflows which has their ownership. So, when we delete that user, all the workflows associated with that user halt making our BAU activities very difficult. It's a hard procedure to find and fix.
If we can assign a default admin who will be assigned all the workflows which have a dependency on the deleted users. In this way, we can delete users without crippling the running workflows. This will ease the process a lot.