This article intends to describe what will happen to user accounts in user of editing delivery group if user accounts have been removed from AD

---

Instructions

In the OnPrem product, the user account will change to a SID from format of domain\username if the account is removed from AD, although it may take several days to do so.

User/machine accounts are never automatically removed from the name cache (even if not referenced).

The command Update-BrokerNameCache -Purge will help remove unused/unreferenced accounts from the site, but it won't help if the account is still explicitly referenced from somewhere.

So you need to remove the user account which has been removed from AD manually from delivery group.