That's not really the nice way to remove it...
First you should do
crontab -u username -l
There you will get a list with everything that is being sheduled by crontab.
You should copy that output to a texteditor and remove the line that calls that webalizer-thingy...
Save that file (eg: in /home/username/cron.txt)
Then run this command:
crontab -u username /home/username/cron.txt
By doing it this way, that job will be removed nicely and the other sheduled jobs will still run.