Happy New Year @tanchev Happy you are here
RUn
$ ls /var/spool/cron/crontabs/
# the result will be: root someuser1234 otheruser2345
$ nano /var/spool/cron/crontabs/someuser1234
$ nano /var/spool/cron/crontabs/otheruser2345
# remove all the cronjobs you do not need
$ service crond restart || sudo service cron restart