You will need to do: sudo passwd root
Then go ahead to set password.
Use the root user using su root
In some Linux systems root login via SSH also disabled in /etc/ssh/sshd_config file
To enable ssh root logging, open the file /etc/ssh/sshd_config.
vi /etc/ssh/sshd_config
Search for the following line and delet the ‘#‘ at the beginning and save the file.
Port 22
PermitRootLogin yes
PasswordAuthentication yes
To save the file
:wq
Restart
