I’m very sorry, I missed the part when you said you didn’t know the user password. My bad!

It sounds like the way that the user space is managed in your bios won’t permit any other alternatives other than the possibility of deleting the user account from the administrator account? Is that possible? You’re not gonna be able to reset that password unless you know it. That’s kind of the point of the password. Unfortunately, it seems that your bios does not allow for you to change the user password, but it may let you delete the account altogether and re-create it with a new password. That however, may cause a bunch of other problems that I can’t really foresee without knowing a lot more information.