With the latest updates for Intune (2. June 2018) Microsoft gave us the possibility to cleanup the devices within Intune depending on the last check in date.
Rules for removing devices
New rules are available that let you automatically remove devices that haven’t checked in for a number of days that you set. To see the new rule, go to the Intune pane, select Devices, and select Device cleanup rules.
It is really quite simple:
Just go to Intune and click on devices. There you find the new option Device cleanup rules
You can now set the threshold. In this case we are going to remove device from Intune if the device not checks in for longer than 180 days
Note: The device is only removed from Intune and not from the Azure AD devices
You will then get a list of the affected devices.