By default , the Guest session is enabled in Ubuntu 11.10 . This tutorial will show you how to remove the Guest session from the logon screen in Ubuntu 11.10.It is not imperative to do ,but its good to remove guest session to maintain privacy .
Step 1: Go to terminal and run the following command to edit lightdm configuration file.
sudo gedit /etc/lightdm/lightdm.conf
Step 2 : Add the following line at the bottom.
Step 3: Restart the system .