In this tutorial, I will be showing you how you can enable root login with openssh-server. To do this, you will need to be logged in to the server as root (or sudo'd). Once in, you will need to edit the ssh config file to permit root login
In this file, you will need to search for the line which says PermitRootLogin. You can do this by using the Ctrl+W command and typing it in. Once you have done this, you will need to ammend the line so that it reads
If this has a # before it, you will need to remove this as it is commenting it out. Once you have done this, you will need to restart ssh.
service ssh restart
You should now be able to log in. If this is a new install and you have not yet enabled root logins on the system, you may want to follow this tutorial which will show you How to Enable root Login on Ubuntu Server