You would have to ask an admin or run another cron. Actually that is a common thing for people to do is leave the cronjob set up to run once or twice a day, and when the new cron fires the script looks for previous versions of itself and kills them prior to running the main loop. This is especially useful if there is a bug in the code that causes it to hang for some reason. The next cron will stop the broken script and start a new version. Here is how I would stop the script with a cron:
killall -u denkorzh >/dev/null 2>&1