How to login to Ubuntu as a root user

"How to login to Ubuntu as a root user?"

Just follow the steps below:

1. Open the terminal and type:
sudo passwd root
2. When you see the prompt that says "Enter new UNIX password", enter the password you want for the root user and confirm it.
3. Type:
sudo gedit /etc/X11/gdm/gdm.conf
4. Locate the line that says "AllowRoot=false". Change it to "AllowRoot=true".
5. Save the file
6. Exit gedit, logout and then reboot