To disable or activate a user account
You must be logged on as an administrator or a member of the Administrators group in order to complete this procedure. If your computer is connected to a network, network policy settings may also prevent you from completing this procedure.
Open Computer Management
In the console tree, click Users.
Computer Management > System Tools > Local Users and Groups > Users
Right-click the user account you want to change, and then click Properties.
Do one of the following:
To disable the selected user account, select the Account is disabled check box.
To activate the selected user account, clear the Account is disabled check box.
To open Computer Management, click Start, and then click Control Panel. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management.
A disabled account still exists, but the user is not permitted to log on. It appears in the details pane, but the icon has an X in it.
When a user account is activated, the user is permitted to log on normally.
The built-in Administrator account cannot be disabled.