root account is locked under Ubuntu Linux. Therefore, you cannot login as root or use
su - command to become a superuser.
You can use below methods to run commands as Adminintrator:
sudobefore each command
sudo -i=> This will start /bin/bash as a root shell so that you can enter a root user command without using sudo command.
sudo passwd root=> Give new password to root and use
su -command to enter in root shell.