First, thank you for your quick reply cyberzork.
FYI I don’t have access to the other computer, so I cannot wipe/erase anything on it but I do want to prevent any unauthorized access should someone starts eM Client on that machine, thus my question.
From the “Manage your Google Account” web page going to the Security setting, then “Your devices”: removing all the devices does force me to login again to my Google account when I use my browser but it does not make any difference to the eM Client i.e. eM Client still have access to my Gmail/Calendar data even if I don’t login again. I believe eM Client always use an OAuth token that gets created on the machine when my Gmail/Calendar account was first added to the eM Client.
Ditto for two steps verification, no impact. eM Client can still access my Gmail/Calendar as if nothing has changed.
Removing eM Client as a 3rd party apps in my Google account does revoke access to eM Client but I believe it does so for all Windows 10 machines since there is only one entry for eM Client as a third-party apps in my Google account (i.e. not one per machine).
For example, after removing eM Client as a third-party apps, if I try to access my Gmail/Calendar account from eM Client again, eM Client opens up my browser automatically and waits for me to sign in to my Google account and register eM Client as a third-party app again. After that, eM Client on that machine gets access to my Gmail/Calendar again without further intervention. Good but…
Since I cannot have access to the second machine and test this, my question is: “By re-enabling eM Client as a third-party apps in my Google account, am I giving back access again to all the machines that used eM Client with my Gmail/Calendar account/OAuth token?” In other words, I think I have only flip the third-party access switch off and on but did not reset anything thus the second machine is still having access.
Clear as mud?