If you ever need to enable the root user in Ubuntu 14.04 LTS linux installation, you can do so as follows:
Open a terminal window and type the following commands:
$ sudo su -c <enter>
# passwd root <enter>
Enter a strong password and restart the computer.
To make sure that you can login as root, open a new terminal window and at the $ prompt, enter:
$ su <enter>
Enter the root password. If you get the # prompt, then you are logged in as the root user.
Now you can manage the system by explicitly logging in as root user.
There could be a need to disable root login. You can do that in a terminal window as follows:
$ sudo passwd -dl root <enter>
