Backend users can delete devices if they are in either the Off Contract or the No Token status (see Token state).
Click the Delete button in the top right corner
Under the Devices tab you will find in the left menu a feature called Deleted Devices.
Here you will be able to find the devices you have deleted, and their current PAC for when you need to re-register them.
Device history will be deleted with the device and will not be visible again - even when the device is re-registered.
Note you can retrieve the PAC of your device on "Device" tab and deleted devices on the left menu. Thanks to this feature, you will have the possibility to re-register your device.