Here is what worked for me, if you have any feedback, please comment.

- How to stop daily/regular backups of the cPanel accounts on the WHM/cPanel server (as a server admin via command line/shell)

uncomment two backup lines from crontab (command: crontab -e) to make them appear like:

#0 1 * * * /usr/local/cpanel/scripts/cpbackup
#0 2 * * * /usr/local/cpanel/bin/backup

- How to disable updates of the WHM/cPanel via command line/shell:

Rename backup script:
mv /scripts/upcp /scripts/upcp-do-not-update

Open crontab editting (crontab -e) and comment out line containing upcp


Do not forget about your changes if you plan to enable it later.