There are a few ways to reset Mac admin password. You can read the guide at How to Reset Mac Admin Password When You Forgot It
How Do I Recover The Master Password On My Apple Mac Os X Laptop Computer?
Hi
There isn't a proper or an official way to recover Mac's lost password.
Nevertheless, there is a workaround it.
Follow these steps to reset the password:
1. Start the machine and on login window, click "Restart"
2. During the computer's restart, press "Command-S" key until you some text scrolling through the window. This will boot the computer into single user mode.
3. You will see "Localhost%" prompt", then type: Passwd [username]
4. The computer will now ask you to type the password twice, so re-enter it.
5. Once you have entered the new password, type: Reboot
6. At the login window, type in the username with the new password.
Once you are logged in, you can then change your user's password and you can create a new user account as well.
Note: This method might not work for newer versions of OS X
Hope it helps?
Source
There isn't a proper or an official way to recover Mac's lost password.
Nevertheless, there is a workaround it.
Follow these steps to reset the password:
1. Start the machine and on login window, click "Restart"
2. During the computer's restart, press "Command-S" key until you some text scrolling through the window. This will boot the computer into single user mode.
3. You will see "Localhost%" prompt", then type: Passwd [username]
4. The computer will now ask you to type the password twice, so re-enter it.
5. Once you have entered the new password, type: Reboot
6. At the login window, type in the username with the new password.
Once you are logged in, you can then change your user's password and you can create a new user account as well.
Note: This method might not work for newer versions of OS X
Hope it helps?
Source