Reset Password
OS X 10.7 Lion,10.8 Mountain Lion,10.9 Yosemite, 10.10 Yosemite and 10.11 El Capitan
Shutdown the computer.
Start the computer,then press and hold down command and R keys to start into recovery partition.
When you see the Apple logo, release the keys.
Wait until OS X Utilities window shows up.
Move the mouse pointer to the menubar at the very top of the screen, click "Utilities” and then select "Terminal"
from the dropdown.
Terminal window will appear.
Type in resetpassword and press enter on the keyboard.
Reset Password Utility window will open.
Quit Terminal.
Select Macintosh HD, if not already.
Select the user account from the popup menu box under “Select user account”.
Enter a new password.
Re-enter the new password for the user.
Enter a hint.
Click the "Save" button.
Click in the menubar and select Restart.
Log in.
When Keychain dialog box appears, select “Create New Keychain”.