Turn off Cortana in Windows 10
------------------------------

1.  Tap on the Windows-key, type: regedit.exe and press enter.
2.  Confirm on the UAC prompt when it displays.
3.  Navigate to: HKLM\Policies\Microsoft\Windows
4.  Look for "Windows Search" (If missing go to step 7.)
5.  In the right pane look for "AllowCortana"
6.  Change the DWORD value to 0 (off)
7.  If "Windows Search" is missing, 
    a. Go to the Edit menu and select new key.
    b. Type "Windows Search" (w/o quotes) as the key's name.
    c. In the right pane add a new DWORD "AllowCortana" (w/o quotes)
    d. Assign "AllowCortana" a DWORD value of 0.  (Verify change.)
8.  Close regedit
9.  Restart Windows 10.  (Cortana isn't allowed to run now.)