[For beginners] [MAC] How to access a locked Mac.

I used to do this in High-School back in the day and thought some of you would like to use it.
Please don't use to get into any stolen computers or something. This tutorial is for educational purposes only.

1) Shut down the computer
2) Start the computer and hold command + s
3) type the following code line by line

Code 
mount -uw /

rm /var/db/.applesetupdone

shutdown -h now

4) Restart the computer
5) Create a new admin account using the setup process that comes in front of you.
6) Wait for the setup to start
7) If you want, you can now change the password of all of the other accounts on the computer.