If you're the only one who uses your computer, and you're not worried about it (or your data) falling into someone else's hands, you may not need the protection that the login screen provides. Here's how to turn it off:

1. Open the User Accounts control panel.
2. Delete any unused accounts that are not your primary, personal account. (Click Manage another account, choose the other accounts, and select Delete the account.) You can ignore the Guest account, which is likely turned off.
3. At the main User Accounts page, ensure that your primary account is active. Click Change your password.
4. Enter your old password where required and leave your new password blank.

Reboot your machine, and it will load Windows directly without presenting the login screen. Just remember that you are compromising your system's security by operating it without a password.

Source : PcWorld News