I understand that you want to remove the domain DEF.Local from your Microsoft Entra sync.
We do not recommend deleting a connector unless there is a strong reason to do so. Since you want to remove a non-existing domain from Microsoft Entra, it may be necessary to delete the connector.
A connector is a link between your identity management system and an external system, such as Microsoft Entra id. It allows for synchronization of objects, such as users and groups, between the two systems. If you choose to delete the connector, it will be removed from the identity management system, but the connector space will still be retained. The objects in the connector space will still exist, but they will not be synchronized to Entra ID.
The connector space is the storage area where the objects from the connected system are held before they are synchronized to the target system. If you choose to delete both the connector and connector space, all objects in the connector space will be deleted, and you will not be able to recover them.
Based on your scenario, where the domain DEF.Local is no longer required and there are no objects in the Active Directory associated with this domain, I suggest selecting the option to delete both the connector and connector space. However, please note that this action cannot be undone, so make sure that you have selected the correct option before confirming the deletion.
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya
If this answers your query, do click Accept Answer
and Yes
for was this answer helpful. And, if you have any further query do let us know.