Run CMD.exe under elevated prompt
Take owner of Narrator.exe and Magnify.exe
takeown /A /F "%WINDIR%\System32\Narrator.exe"
takeown /A /F "%WINDIR%\System32\Magnify.exe"
Deny everyone execute them
icacls "%WINDIR%\System32\Narrator.exe" /deny *S-1-1-0:(X)
icacls "%WINDIR%\System32\Magnify.exe" /deny *S-1-1-0:(X)
Done!