“sudo” command can used to enable “root” user and execute any command via “root” account.

$ sudo
usage: sudo -K | -L | -V | -h | -k | -l | -v
usage: sudo [-HPSb] [-p prompt] [-u username|#uid]
{ -e file [...] | -i | -s | <command> }

Here is how you enable the “root” account. You should need an Admin previledged account.

1. Command + spacebar -> typein  “Terminal” or Macintosh HD -> Applications -> Utilities -> Terminal.
2. Execute the following Command “sudo passwd root”

$ sudo passwd root
Password:
Changing password for root.
New password:
Retype new password:
$

Once the command prompt is shown, you can now login using the “root” in the terminal or while your mac boots up ( if you have manual login ).