Windows 10 continues to communicate with Microsoft’s servers even after users change privacy settings. Cortana and Bing search continue to send data to the company’s servers. Cortana sends information containing user’s identifying computer ID that persists across reboots. Microsoft said all communications between a Windows 10 machine and Microsoft are only to make the retrieval of updates easier. Even if users clear all the Tiles in the Start menu, Windows 10 re-install new tile info from Microsoft from Windows 10, which is more troublesome.
Source: https://thehackernews.com/2015/08/windows-10-privacy-spying.html