Enabling The Root Account
By default the root account is disabled, but you can enable it by using this command and giving it a password
sudo passwd root
Now you can log into your pi as the root user. Whilst this opens up security concerns its sometimes very useful, for instance when developing with netbeans and remotely running applicaiotn that access the IO pins.
If it doesn’t work check the ssh config
sudo nano /etc/ssh/sshd_config
Search for PermitRootLogin and change it to yes
You can undo logging in as root again using this command
sudo passwd -l root