Ubuntu fresh installations have the guest account enabled by default. This caused me few problem already and not really happy about it. So, after searching and learning about this I found that there is a simple solution for it.
Start a terminal session using Alt+Ctrl+t or any other way you know,
in the terminal type the following
gksudo gedit /etc/lightdm/lightdm.conf
This command will open gedit editor with the file lightdm.conf for editing
Also, it will require root access, so your account must be in the sudoers account.
Now add the following line to the lightdm.conf file
allow-guest=false
This line will disable the guest account on this computer.
Then you should restart the lightdm using this command
sudo restart lightdm
This process is very well everywhere on the internet if you search for it, but, I like to add my own to make it easier to find and track later.
