Creating SuperUser/root user in Ubuntu

in the terminal write

$sudo

insert your pasword
and
root passwd

and you define your root pasword

or

$ sudo passwd root
[sudo] password for existing user
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Disable super user account password on Ubuntu

Later if you don’t want to use su anymore, you can lock the root user password using one of the methods shown below

$ sudo passwd -l root

( or )

$ sudo usermod -p '!' root