I installed only Word/ Excel, and none other apps (not OneDrive)
OneDrive is installed by default by Windows 10. You might want to verify you don't actually have it installed since it can be removed, but that isn't the focus of this question. Even if you disable the OneDrive Windows 10 client, I don't believe it's required, for the OneDrive functionality within Office. Additionally, only OneDrive Business is installed by Office which is slightly different than the built-in OneDrive client on Windows 10.
when I run word/ excel - Open, it still shows OneDrive and my email is there.
This is due to the fact you are actually logged into your Microsoft account.
I hadn't even installed OneDrive, let alone signing in to that, so I didn't even give my OneDrive password to Office 2019, how it reached there?
OneDrive is installed by default on Windows 10. OneDrive is connected to your Microsoft Account, which you are clearly logged into since you removed your account information from your screenshot.
Probably it didn't uninstall office 2016 fully and picked my settings from that.
Office 2016 and Office 2019 can exist on the same system, although this will cause problems, with applications like iCloud. In any event, the settings between the two applications, are actually indeed separate.
There is no option appearing in ms word to disconnect syncing to OneDrive or to logout of it.
There wasn't an option to remove the OneDrive, from the list of locations, where a file can be saved in Office 2016. However, if you log out of your account, it will find you will be asked to log into your account before a file can be saved to that location.
here is no option appearing in ms word to disconnect syncing to OneDrive or to sign out of it.
There absolutely is an option to sign out of your Microsoft Account within Office. However, based on the build you actually have installed, you have Office 365 installed instead of Office 2019 (which is a specific Office 365 build from October 2018). Office 2019 is identical to Office 365 except you don't get incremental monthly builds with an Office 2019 license. This is all documented by Microsoft, and I have already spent hours researching it and submitting an answer to that very topic.
work on clients' files, and some clients have strongly worded
Non-Discloser Agreement stating that I am not to put/ share their
files on net. so, I am worried that some hacking might get my clients'
material stolen and I will be in deep trouble.
You should just change the default location.
Click the File tab, and then click Options.
In the first section, type the path in the Default local file location box
Set a default working folder
how to stop MS office syncing to onedrive. Onedrive should not be visible to me anywhere within MS Office.
OneDrive is now intergrated into Office and it cannot be removed. It has been intergrated since I believe Office 2013. The only new change is the default location.
Starting as early as next month, Microsoft plans to change Office 365's default document-saving behavior to OneDrive and OneDrive for Business folder locations.
OneDrive To Become Office 365's Default 'Save' Location