I have the exact same issue. Brand new fresh-out-of-the-box Dell OptiPlex 7050 PC, Dell "OEM" Microsoft Office Home and Business 2016 installation. There is no "Mail" icon in Control Panel, nor is Office 2016 even listed on the Programs and Features/Remove list.
It's like Dell's shipping half-baked Office installs with these latest systems. Outlook just gets some bogus "can't find that user" type error when launching and entering verified-correct e-mail credentials for Office 365. Can't set up the mail account manually because there's no mail icon in Control Panel. Can't uninstall because there's no Office H&B listed in Control Panel.
Looks like Dell just screwed up all things Office. I'm going to just try to log in directly to Office.com/Account and see if I can manually download/install from there.
-Dan