Today tip will help you to clear the history of windows logon screen
because when you boot up into windows 2000 or XP. Windows shows the
information about the last user logon to that computer in the user name
field. But you can disable this option to show the last user logon
information, if you have little knowledge about editing windows registry.
Follow the given steps to clear the history of last logon user:
To use this feature, you will need to be logged into your computer with
administrative rights.
First click on Start button then type Regedit in Run option.

Here locate the location to:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System
HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

Here in right side panel, double click on dontdisplaylastusername
option and change its value data to 1.

Now close the registry editor and restart your computer after any
changes to go into effect.
But next time, if you want to enable this feature then
you can change its value 0 to display username again.