2 user accounts in my name on fresh installation win10 - how to disable or restrict the second one

Solution 1:

I have installed windows 10 pro with first account which has some login and is under my name. But after some time I saw there is one more account under my name which I cannot edit in lusrmgr because it is invisible there. I can see this account for example at security tab of some start folders.

What you describe is perfectly normally. When you created your account a local account that exists on your machine was created. The account jtrav was created on a machine called ABCDE. A new account was also created when you linked jtrav` to your Microsoft Account.

How can I manage to have just one account there? Or if not possible, how to add zero rights to the second one?

You could remove jtrav from the ACL if you wanted, but I don't suggest you do that, it has permissions in the event you unlink your Microsoft Account. You should proceed with caution if you go against this recommendation.

For example I have two accounts on my computer. Lets suppose my name is John Travolta. My initial account which I created is ABCDE/jtrav. On some folders, especially at start menu, I see there are two accounts with some rights on it.

First one is ABCDE/jtrav and second one is "John Travolta" and it has different rights to that folder.

ABCDE/jtrav indicates the account only exists on that specific machine while John Travolta is an indication the account is linked to a Microsoft Account. They are the same exact account. Once you link a local account to a Microsoft Account, only the Microsoft Account can be managed, ABCDE/jtrav still technically exists but it cannot be used to access your system.

It's unnecessary to modify the permissions of ABCDE/jtrav especially on a folder like the Start Menu.