Disable motd news on Ubuntu 18.04

Edit this file vim /etc/default/motd-news:

Change ENABLED=1 to ENABLED=0

Remove the rigth to execute on those files:

chmod -x /etc/update-motd.d/80-livepatch
chmod -x /etc/update-motd.d/51-cloudguest
chmod -x /etc/update-motd.d/10-help-text