Information
Enabling the root account puts the system at risk since any exploit would have unlimited access privileges within the system. Using the sudo command allows users to perform functions as a root user while limiting and password protecting the access privileges. By default the root account is not enabled on a Mac OS X client computer. It is enabled on Mac OS X Server. An administrator can escalate privileges using the sudo command (use -s or -i to get a root shell).
Solution
Open System Preferences, Users & Groups. Click the lock icon to unlock it. In the Network Account Server section, click Join or Edit. Click Open Directory Utility. Click the lock icon to unlock it. Select the Edit menu > Disable Root User.