While it's possible to do, it is not recommended.
To actually enable root logins first you have to set a password for the root account and then unlock the locked root account. If you don't set a password for the root account the
passwdcommand will return
passwd: unlocking the password would result in a passwordless account.
So, first execute in a terminal
sudo passwd root
you will be prompted for a new Unix password. Write it twice (second for confirmation).
sudo passwd -u root
to unlock the account. This should return
passwd: password expiry information changed
If you want to disable root account in Ubuntu you need to lock the root account by using the following command
sudo passwd -l root
Alternatives to root login
If you want to work on a root console you can also use
Only do this if you know what you are doing. More information on why to stay with sudo here
Graphical version needs setting up 1st:
pkexec gnome-terminal will open a terminal with a root prompt.
passwd root will allow you to create a password for root.
Note: Running users-admin with elevated privileges no longer works because of a bug that is marked as "Won't Fix" for security reasons. Seehttps://bugs.launchpad.net/ubuntu/+source/gnome-system-tools/+bug/685215 for an explanation.
pkexec users-admin will open the users screen: