If you found another person’s iCloud locked iPad, try to return it to the owner.
This manual will help you with the iCloud bypass on your iPad Air 2 Cellular. After bypass iCloud, you will have iPad Wi-Fi Only. Sim-slot will not work. GPS and Bluetooth will work. Wi-Fi will work only after jailbreaking iOS and replacing files inside iOS.
First, disassemble iCloud locked iPad Air 2.
If you are looking for not hardware iCloud bypass method you can try another way for ALL iCloud locked devices.
If you are looking for a way to unlock the iCloud on iPad Wi-Fi Only, iPhone or iPod, then read this article: How to bypass iCloud on iPad WiFi, iPad Cellular, iPhone and iPod.
At this moment this method doesn’t work with new iOS 11. Apple has patched even rsim. There is only a loophole with iPads WiFi only with iOS 10. Waiting… Don’t update your iCloud bypassed iPads.