Log in to your account as an administrator. Click "Start" and then "Run" to enable the command line utility. Type "control userpasswords2" in the "Run" box. Press Enter on your keyboard. Uncheck the box that is labeled "Users must enter a user name and password to enter this computer". Press OK. Next time you log on to your computer, the unlock computer screen will not appear.

if this method didn't work, try UUkeys windows password mate to create a reset disk with USB.

Source: http://www.uukeys.com/reset-windows-10-password.html

Another way is try Command Prompt.