Sick of Windows Messenger from signing into your MSN account automatically? This is how you can remove it from saving the username and password.
Click on Start
Click on Control Panel
Click on User Accounts
Select the User Account that messenger signs in on.
Select Manage my Network Passwords under Related Tasks near the Home Button.
The Stored User Names and Passwords dialog window will pop up.
Select your MSN account such as “firstname.lastname@example.org [Passport]” and choose Remove then Ok in the confirmation dialog.
Click Close and you are done.