Lock Windows 10 PC remotely

Solution
Connect with remote desktop. It automatically disconnects locally connected user.
Then you can logout local user and disable local user account, to prevent further logins (of course - your brother needs to use his own account, you can't share your admin account with him).

Requirement for this to work - Windows 10 Pro. Feature is not available on Windows 10 Home version.
Connect with remote desktop. It automatically disconnects locally connected user.
Then you can logout local user and disable local user account, to prevent further logins (of course - your brother needs to use his own account, you can't share your admin account with him).

Requirement for this to work - Windows 10 Pro. Feature is not available on Windows 10 Home version.
 
Solution