@all
Thanks for your feedback and sorry for the inconvenience this might have caused.
AirDroid running in the background is for the purpose that when you sign in to web.airdroid.com, AirDroid app will launch automatically on your device.
If you want to kill the process, you may try some 3rd party Task Manager. But please note that if you've enabled "Find Phone" in AirDroid, the process cannot be killed by any 3rd party Task Managers.