Q: Removing the a/c

Sounds like the device has an Activation Lock on it.  It's a security measure.  You can read more about it here -- iCloud: Activation Lock & Find My iPhone Activation Lock - Apple Support

If you cannot find the previous owner of the device, and you cannot return the device for a refund assuming it was purchased second-hand, then the device is simply a dud and would be totally useless to you.