If you are like me, and are using one of the Ubuntu linux varieties (I use Xbuntu), then you may have noticed that the guest account has been turned on by default. This is somewhat of a security ooops, and even if you are the only one with physical access to your computer, you should disable that guest account.
open your terminal and type the following command.
sudo pico /etc/lightdm/lightdm.conf
enter your password to gain root access to the file.
add this line to the end of the config file:
so your default config file should look like
press <ctrl><x> then <y> (to save changes) and <enter> to save the file
when you log out, you will notice you no longer have the option of guest account for login.