I will include screen captures related to OneDrive in order to try to make some things a bit clearer. But, before that, I want to make a couple of points:
1. If you don't want individuals with whom you share your actual computer to have access to your OneDrive then the best thing to do is to give each person who's using the machine their own user account, whether that's a local account or one associated with a Microsoft Account. If you don't have a Microsoft Account then you can't use OneDrive, since the cloud part of OneDrive is associated with a Microsoft Account.
2. One Drive is "lockable," but it really isn't intended to be used that way. The idea behind OneDrive is for a user to have important (or unimportant) files stored in the cloud and immediately available to them on any Windows 10 (or 8, I believe) computer on which they log in with a Microsoft Account associated User Account.
I do not use OneDrive, so I started it again so I could include images related to OneDrive but I forgot this forum doesn't support direct inclusion of pictures.
The OneDrive Clouds icon in the system tray will be gray, not blue, when One Drive is running but not logged in.
If you right click on the OneDrive icon in the system tray and select Settings, and look at the Settings tab, you'll see there's a checkbox that allows you to select whether OneDrive starts automatically when Windows starts (for your individual account).
Once you have logged into OneDrive, even once, your account information is retained so that, if you're using OneDrive as most people do, the things that you put in the OneDrive folder on your computer are automatically uploaded/synchronized to their cloud equivalents. This is what most people want since OneDrive is associated with a given Microsoft Account (and that usually maps to a User Account on a Windows computer).
If you want to be logged out of the sync process until/unless you log in again, press the "Unlink OneDrive" button. This logs you out and throws away your stored login information. Be aware, though, that if you log in again you need to repeat this process again, since the typical way OneDrive is used means that seamless synchronization is wanted (you don't seem to want this).
In the final analysis, if you don't want people to have access to your OneDrive files, and you share a computer with other people, each person should have their own User Account on that machine. There are other advantages to that arrangement as well, as each user can customize their desktops as they see fit (among other things) without having any effect on yours (or those of other users on the computer).
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1809, Build 17763
Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.
~ Mark Twain