How can I recover my administrator ID in my iMac?

Question

Hi
I forget my password of administrator in my iMac, so I can`t make changes
How can I recover it?

Answer 1

Forgot Your Account Password
For Lion, Mountain Lion, or Mavericks
    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
       OS X Mountain Lion- Reset a login password,
       OS X Mavericks- Solve password problems,
       OS X Lion- Apple ID can be used to reset your user account password.
For Snow Leopard and earlier with installer DVD
     Mac OS X 10.6- If you forget your administrator password,
     OS X- Changing or resetting an account password (Snow Leopard and earlier).
For Snow Leopard and earlier without installer DVD
    How to reset your Mac OS X password without an installer disc | MacYourself
    Reset OS X Password Without an OS X CD — Tech News and Analysis
    How To Create A New Administrator Account - Hack Mac