How to remove permanently those error prompts while using openbox gnome? Such as: update ubuntu latest release, this kind of errors etc, how to permanently disable them so that it does not show in front of my presentation.

Follow up:

a) How do i kill that screen shot error box?

$ cat /etc/default/whoopsie

[General]
report_crashes=false

$ apport-cli

*** Send problem report to the developers?

After the problem report has been sent, please fill out the form in the
automatically opened web browser.

What would you like to do? Your options are:
  S: Send report (69.7 KB)
  V: View report
  K: Keep report file for sending later or copying to somewhere else
  I: Cancel and ignore future crashes of this program version
  C: Cancel
Please choose (S/V/K/I/C): I

b) How do i kill that update notification dialog box?

$/etc/xdg/autostart# vim update-notifier.desktop 
#NoDisplay=true
NoDisplay=false
:wq

$ cat update-notifier.desktop | grep NoDisplay
NoDisplay=false

No more disturbing popup's now.