Once you retire a device from Ivanti Neurons for MDM, it is unenrolled from Lookout since it no longer has the required Ivanti Neurons for MDM custom attributes. This automatically deletes the device from Lookout if you have the Delete device on unenrollment setting enabled in the Enrollment Management tab of your Connector settings.

Once a device is deleted from Lookout, you can re-activate and re-enroll the device by adding it back to Ivanti Neurons for MDM with the required custom attributes.