Binary Expressions

If you would like to remove the list of user accounts and force users to login using their username and password, change the following settings:

1. Go to Start Menu -> Settings -> Control Panel -> Administrative Tools -> Local Security Policy.
2. Local Policies -> Security Options.
3. Double click the entry titled: “Interactive Login: Do not display last user name”.
4. Place a check mark in the “Enabled” check box.
5. Click OK and close “Local Security Policy” window.

Source: Make users to login with a user name and password