how to delete it?

now i know how to make a cron job in php

exec("echo '* * * * * /usr/local/bin/php -f /home/survey/public_html/john/cron/snd2.php' | crontab -");

i want now to know how to delete this cron job from cpanel but also using my php code..

any help??

echo exec('crontab -r') ??

See this ...
http://stackoverflow.com/questions/4421020/use-php-to-create-edit-and-delete-crontab-jobs