Please refer to the steps given below to enable root users in Ubuntu –
1. Log in to your Ubuntu server using the default user from the console.
2. Go to the sshd_config file at the /etc/ssh/ path.
3. Comment #PermitRootLogin without password, and add PermitRootLogin yes into the line.
4. Restart the SSH service to effect the changes by using this command –
service sshd restart
You have enabled Root user in Ubuntu.