Use one of the following method.
Using Terminal Commands:
Here’s how to reset your OS X password without an OS X CD.
You need to go to terminal window and create a new admin account:
2. Hold apple key + s key down after you hear the chime.
(Command + s keys on newer Macs)
3. When you get text prompt enter in these terminal commands to create a brand new admin account (hitting return after each line):
mount -uw /
shutdown -h now
4. Your computer will shut down and reboot. A setup window should pop up asking what language you want your computer to be in, just as if you turned on your computer for the first time after purchase. (Be sure to select “DO NOT TRANSFER MY DATA”.)
5. Near the end of the setup you will be asked to create an administrator account for your computer.
6. At that point computer will automatically log you in using your new administrator account. With this account you will be able to change the password on the old administrator account.
Booting From Recovery Partition:
Boot to your Recovery Partition, by holding down the Option key (Command-R) while starting, and then selecting the Recovery HD as the boot choice.
Once booted, at the top of the screen is a menu …, select Utilities / Terminal from the menu bar.
In the Terminal window, type “resetpassword” (without the quotes) and press return. A “Reset Password” window will open. Select your boot volume (your SSD drive) if it is not already selected. Select your administrators username from the menu labeled “Select the user account” if it is not already selected. Follow the prompts to reset the password. Restart the computer from the apple menu.