By default you can no longer login using ssh as root with just a password since it is more secure to use a pre-shared key. However, you can you can still enable root logins using password authentication.
To do this you need to edit the ssh config file ‘/etc/ssh/sshd_config/sshd_config’ as root.
# vi /etc/ssh/sshd_config
Then find the entry in the Authentication section of the file that says ‘PermitRootLogin’ and change ‘without-password’ to ‘yes’.
# Authentication: LoginGraceTime 120 #PermitRootLogin without-password PermitRootLogin yes StrictModes yes
Note – It is just a personal preference but when making this sort of change I prefer to comment out the original entry and create a new one.
You will need to restart the SSH server (or reboot) for this change to take effect.
# service sshd restart