Microsoft is auto-downloading Windows 10 installation files onto users’ PCs even if they have not opted into the upgrade. Microsoft plans to deploy Windows 10 on over 1 Billion devices worldwide. Microsoft is not only consuming storage space but also using user’s Internet bandwidth for large unrequested files, as the Windows 10 installer downloads up to 6 gigabytes. Users can simply choose to disable downloading of all Windows updates. Windows 8.1 has a setting for metered connections, but it only works for Wi Fi and mobile broadband networks, not for users connected with.
Source: https://thehackernews.com/2015/09/how-to-windows-10.html