Here are three steps to enable the root account in Kubuntu.

First, open the file /etc/kde4/kdm/kdmrc with your favorite text editor.  Within the file find AllowRootLogin=false and change it to AllowRootLogin=true.  Save and close the file.

Now you have to change the root password.  To do this, simply write the following command in the Konsole:  #passwd root.  It will prompt you to type your new Unix password.  Always make sure that you have a proper password.  Your password’s complexity will dictate how long it will take for your computer to be hacked.,

Reboot and voilà, root is enable.