I have forgot my Administrator Password

1. Restart your Mac.
2. Quickly Hold both Command + R at the same time
3. Once booted into macOS Recovery, Go to Utilities Menu Bar, Then Click Terminal
4. In Terminal, Type this below:

resetpassword

5.Press Enter

6.Click Forgot All Passwords.

7.On your Admin Account click Create.

8.Enter your new password

9.Do the same thing for other Users as well.

10.Click Exit

11.Restart 

Follow the instructions:

1) Restart your mac

2) Quickly hold down Command + R at the same time

3) When booted into MacOS Recover, Go to Utilities Menu Bar, Then click Terminal

4) In Terminal type this below:

resetpassword

5) Press Enter/Return

6) Click Forgot All Passwords

7) On your Admin Account click Create.

8) Enter your new password

9) Do the same thing for other Users as well.

10) Click Exit

11) Restart

I hope this helped!

+1 :-)