Revoke app assignments in Apple Configurator 2
You can revoke an app assignment.
In Apple Configurator 2
on your Mac, choose Account > Sign In, then sign in to the App Store with an Apple School Manager or Apple Business Manager account that has permissions to buy apps and books.You must have a license for each device that the app is assigned to.
WARNING: If you’re using an older VPP account that’s already associated with an instance of Profile Manager, all app assignments from that association will be revoked. If your older VPP account is already associated with a third-party MDM solution, consult the MDM vendor before you sign in with the Apple ID associated with your VPP account or the Apple ID associated with a purchaser you specify.
Choose Window > Volume Purchasing Assignments.
Click the disclosure triangle next to an app to view the serial number of the devices the app is assigned to.
Select a device in the list, click the Remove button in the toolbar, then click Revoke.
The app is now available to be assigned to another device.