Updated: 2016-Aug

For Ubuntu 16.04 LTS (15.10 or later)

Adapted from: LightDM Ubuntu Wiki - Configuration

• System provided configuration files in /usr/share/lightdm/ are not intended to be user editable. Instead users should use: /etc/lightdm/


• Newer versions of LightDM (Ubuntu 15.10, or later) use [Seat:*] instead of [SeatDefaults]

Just run this (once) at terminal:

sudo sh -c 'printf "[Seat:*]

allow-guest=false

" >/etc/lightdm/lightdm.conf.d/50-no-guest.conf'

To undo (restore Guest option), remove the file created:

sudo rm /etc/lightdm/lightdm.conf.d/50-no-guest.conf

For Ubuntu 14.04 LTS (up to 15.04)

Adapted from: Ubuntu Forums - lightdm config files location in 14.04

Just run this (once) at terminal:

sudo sh -c 'printf "[SeatDefaults]

allow-guest=false

" >/usr/share/lightdm/lightdm.conf.d/50-no-guest.conf'

You will no longer have 'Guest' as login option, on your next login.

To undo (restore Guest option), remove the file created:

sudo rm /usr/share/lightdm/lightdm.conf.d/50-no-guest.conf

For Ubuntu 12.04 LTS (up to 13.10)

Simplest method.

Just run this (once) at terminal:

sudo /usr/lib/lightdm/lightdm-set-defaults -l false

You will no longer have 'Guest' as login option, on your next login.

• This simply appends allow-guest=false to /etc/lightdm/lightdm.conf.

  
  



• Should work from 11.10 onwards (since these use LightDM as well).

  
  

To undo (restore Guest option):

sudo /usr/lib/lightdm/lightdm-set-defaults -l true