how to delete a device from airdoid

if you cannot see an x beside the device name in the options/settings of your airdroid web sessoin:
-sign out from the web session on the computer
-sign in on the new device: install the app on the new phone, sign in by selecting web session and entering your credentials.
-now go back to the computer and refresh the page, you will sign in to the new device in the pc and can see its content. Now if you open the 'devices' tab, you will see the new device and the old device. The old device is now removable. Ditch it. Done.