Reset forgotten OS X Mavericks 10.9 admin password

The passwords for all accounts on OSX 10.9 Mavericks and OSX 10.8 Mountain Lion including admin and standard users can be reset and changed when booted from the Recovery Partition on OSX.

Boot into recovery partition:

Reboot into the Recovery Drive by choosing the ‘Apple’ menu > Restart, hold down the ‘command’ + ‘r’ keys or alt key on the keyboard during the start up process when you see the start up screen you can let go. When the machine boots eventually you will see the OS X Utilities screen.

 

Select Terminal from the Utilities menu

At the command line, type 'resetpassword' and hit enter

This launches the Reset Password screen, select the Volume Hard Drive in the top part of the window pane, then for the user that you need to reset select the user account in the lower part then add and confirm the new password and click save, you get a confirmation screen and details about the keychain account.

Go to the Apple Menu and click Restart to boot back to the normal hard drive and the new password will take effect immediately.