Canonical thought it to be best to prevent user from logging in as root completely. Though it has certain advantages of not letting users modifying critical settings and crashing their systems, but home users quickly turn into power users and then they need root user for many tasks. Enabling root user login is however really easy.

Follow the steps below to quickly enable the root user login.

Step 1: Setup a root user password from any user account->

Unlock this screen using user password.

Open root user properties:

Setup the password:

Step 2: modify the login window so that it can accept the root user.

Enable root user login