How to prevent a kiosk running Ubuntu 13.10 showing the update dialog popup window?

In my KIOSK i have Ubuntu 13.10.

How to remove/suspend/blacklist/hide/disable completely from the Ubuntu 13.10 this following popup via command line? (even with GUI when i click settings and insert my password it still fails and keep repeating it)

• this setup is running in a busy Railway, where passengers passing very busy place every day almost every hour i have this strange popup "Software update" even i do not want it

Please kindly anyone suggest how to remove this to stop disturbing? I have tried following but none works:

root@touch:~# vim /etc/default/grub 
add GRUB_RECORDFAIL_TIMEOUT=0
root@touch:~# vim /etc/default/apport 
put 0
root@touch:~# sudo sed -i 's/NoDisplay=true/NoDisplay=false/g' /etc/xdg/autostart/*.desktop
root@touch:~# 

• install dconf-editor by typing : sudo apt-get install dconf-editor `

• Now open it using: sudo dconf-editor

• go to com->ubuntu->update-notifer-> no-show-notifications and enable it

.

You can do that same using command line by typing :dconf write /com/ubuntu/update-notifier/no-show-notifations true