if you mean a account password then:
start windows xp in safe mode: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/boot_failsafe.mspx?mfr=true
click on administrator account
click on the start button
Now go to control panel.
Click on User Accounts
Click on your name(the account you want to delete the pass)
Remove the password.
then restart your pc and boot the normal way and the password should be deleted