Forgot Admin Password 10.4.11
I forgot the administrator password for an older G3 Tower running 10.4.11, how do I reset?
Forgot Your Account Password
For Snow Leopard and earlier
Mac OS X 10.6- If you forget your administrator password
For Lion/Mountain Lion
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
When the menubar appears select Terminal from the Utilities menu.
Enter resetpassword at the prompt and press RETURN. Follow
instructions in the dialog window that will appear.
Or see Reset a Mac OS X 10.7 Lion Password and
OS X Lion- Apple ID can be used to reset your user account password.