If the AutoAdminLogon key is present under HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon and contain "1" then you can use AutoLogonCount key value to control the automatic logon next time.
AutoLogonCount will determine the number of automatic logons that occur. Each time the system is rebooted, the value of AutoLogonCount is decremented by one, until it reaches zero. When AutoLogonCount reaches zero, no account will be logged on automatically, the AutoLogonCount key value and DefaultPassword key value, if used, will be deleted from the registry and AutoAdminLogon will be set to zero.
So you can set the value of AutoLogonCount to 1 and once the machine has rebooted the new value will be 0 and next time automatic logon will be disabled.
Note: The automatic logon occurs only when the computer is rebooted, not when the user logs off