Removing Guest Session at login in Ubuntu 14.04

Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo nano /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

Add the following line, save and then close.

allow-guest=false

Reboot, and you're set.

Edit

Thanks to Gunnar Hjalmarsson

Based on Gunnar Hjalmarsson comment "ubuntu-session was last updated in the middle of March. Try sudo apt-get install --reinstall ubuntu-session" when that is done, the Guest session returns.

After some research, this can be done a different way as well.

Open /etc/lightdm/lightdm.conf file from your terminal using the following command:

sudo -H gedit /etc/lightdm/lightdm.conf

If the file exists, then just add the following line:

allow-guest=false

Otherwise copy and paste the following into it:

[SeatDefaults]
user-session=ubuntu
greeter-session=unity-greeter
allow-guest=false

Save the file and exit the editor. Reboot your system, and the changes will remain even after an update to ubuntu-session as mentioned by Gunnar Hjalmarsson's comment.

To remove guest login :

1. sudo sh -c 'printf "[SeatDefaults]\nallow-guest=false\n" > /etc/lightdm/lightdm.conf.d/50-no-guest.conf'

2. This will create a new file in /etc/lightdm/lightdm.conf.d

3. To get back guest login again remove 50-no-guest.conf

To remove remote login :

1. sudo sh -c 'printf "[SeatDefaults]\ngreeter-show-remote-login=false\n" >/etc/lightdm/lightdm.conf.d/50-no-remote-login.conf'

2. This will create a new file in /etc/lightdm/lightdm.conf.d

3. To get back remote login again remove 50-no-remote-login.conf