Uninstall

remove sniffer (first make sure the sniffer service is stopped)

rm /usr/local/sbin/voipmonitor
rm /etc/init.d/voipmonitor
rm /etc/voipmonitor.conf

update systemd if its present in system after init script removed

systemctl daemon-reload

remove GUI - it depends on where it is installed. Usually in /var/www/html or /var/www

drop database voipmonitor

mysqladmin drop voipmonitor

remove cron voipmonitor line from

/etc/crontab