Delete a third-party MDM server in Apple Business Manager
You can delete a third-party mobile device management (MDM) server and reassign or unassign devices that are currently assigned to it.
Important: If a third-party MDM server that has devices assigned to it goes offline instead of being deleted (for example, due to a network issue), devices associated with that server are managed with the last known configuration until they are assigned to a new server, or are erased and reactivated.
Delete a third-party MDM server
In Apple Business Manager
, sign in as a user that has the role of Administrator or Device Enrolment Manager.Tap your name at the bottom of the sidebar, tap Preferences
, then select your MDM server 
under the Your MDM Servers list.Tap the Delete button
, then do one of the following:Select the MDM server that the devices will be reassigned to, then tap Reassign & Delete.
Select None from the MDM server list, then tap Unassign & Delete.