Unassign devices in Apple Business Manager
You can unassign devices from a mobile device management (MDM) server. For example, if a device is moved from one location to another, you can unassign it from one MDM server and assign it to another MDM server. If you keep the device in the programme, it simply becomes associated with another MDM server. You can also unassign devices by removing the MDM server they are associated with.
In Apple Business Manager , tap Device Assignments in the sidebar and choose the method for device unassignment:
If you choose Serial Number: enter each serial number separated by a comma.
If you choose Order Number: view the quantity and type of devices.
If you choose Upload CSV File: you also upload a comma-separated value (.csv) file that contains a list of device serial numbers.
Choose Unassign Devices from the Perform Action pop-up menu, then tap Done.
You can reassign devices to a different MDM server at any time.