Disable update notifier

I'm trying to disable the update notifier completely. Unfortunately the GUI options does not allow this.

I found this hint:

$ sudo apt purge update-notifier update-notifier-common

but it asks for the removal also of:

The following packages will be REMOVED:  ttf-mscorefonts-installer* ubuntu-desktop* ubuntu-desktop-minimal*  ubuntu-release-upgrader-gtk* update-manager* update-notifier*  update-notifier-common*

I'm not sure it's correct to remove, say, ubuntu-desktop. In fact:

$ dpkg -l | grep ubuntu-desktopii  ubuntu-desktop                             1.472                                      amd64        The Ubuntu desktop systemii  ubuntu-desktop-minimal                     1.472                                      amd64        The Ubuntu desktop minimal system

They are the desktop system packages.Before making a mess in the computer, would you please help me to understand how to get rid of any notifications about updates?

I just want to check and install them manually from command line.