To get started, hit Ctrl+Alt+T, copy and paste this command into terminal and hit enter:
sudo passwd root
Input current user’s password, then input a root password twice. Typing in your password does not show in terminal, just blindly type in your password and hit enter.
Enable Login as Root account in LightDM:
Root account won’t shown as a user in Ubuntu LightDM login screen, so you need to manually type in username and password. To enable it:
Edit “/etc/lightdm/lightdm.conf” with this command:
gksudo gedit /etc/lightdm/lightdm.conf
Then add this line to the end and save the file.
greeter-show-manual-login=true
Now restart your computer, choose Login and type in root and password to login as root.
Enjoy!