Hello,
How is the best way to achieve cleaning the device after 90 days without connecting ? I want to implement this policy.
Define cleaning? Do you mean remove the device from the list? If that is your goal, there is no built-in mechanism to do this. You can write a script to do so. Query the NBI for devices where the _lastInform is on or before the date in question. Then you can spin through the _id in the output and send a DELETE to the server for that device id.