Turn off your Mac.
Hold down Command + R (⌘R) key combination, and click the start button until logo appears, into recovery mode (Recovery Mode) (Of course, you can also press the power button, after you hear the startup tone, immediately press live ⌘R key).
Select "Simplified Chinese as the main language" (or other languages), click the right arrow. Select "Terminal" in the "Utilities" menu bar.
Input command (Note: ligatures, and lower case letters): In the terminal ResetPassword, press Enter.
Window, select the appearance of "password reset" boot disk files containing passwords, hoping to reset user accounts; user to enter and confirm a new password, and message (optional) to set a password; click "Reset Assume".
Click menu bar, and select "reboot" or "off." Next time you start using your new password to.
Boot prompt choose to use the new keys to string