Resetting Your OS X Password
If you have misplaced, forgotten, or do not know any of the administrative passwords on your own OS X computer, resetting it is quite simple.
To do this, you will need an OS X Installation CD that will start up your computer. It is best to use the version of OS X that most closely matches the version you are currently running. One of these comes with all Macintoshes that shipped with OS X installed; if yours did not ship with OS X, you most likely bought a copy of Jaguar (OS X 10.2; this comes in a white box) or Panther (OS X10.3; a black box).
– Insert the Mac OS X Installer disk.
– When you hear the startup tone, hold down the C key until you see the spinning gear.
– When the Installer appears, choose “Reset Password” from the “Installer” (for 10.3) menu. Note that for 10.4 the menu is called “Utilities.”
– Follow the onscreen instructions to change the password.
– Quit the Installer and restart your computer while holding down the mouse button (this will eject the CD and prevent you from going back into the installer again).