Backstage View in MS-Word 2010 & Later
As I suspected, you really can't turn it off in its entirety, and I actually wouldn't want to myself.
for some information on keyboard shortcuts you can use to get just the file navigator to show up when you want to "Save as" or "Open" and have set the option to not show Backstage View to On.
Where that option is controlled clearly varies for versions of Word after 2010, as the location noted in the article referenced above does not contain it for Word 2010.
Brian - Windows 10 Home, 64-Bit, Version 1703, Build 15063 (dot level on request - it changes too often to keep in signature)
The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.
~ Niels Bohr