help for a crontab

[fuffy]

crontab help

Hi

I have a little problem

i must add a crontab for clean log_error


can you help me for write this command?

i have add this code

50 15 * * * : > /var/www/vhosts/*/statistics/logs/error_log

and this (not recommended)

50 15 * * * rm -f /var/www/vhosts/*/statistics/logs/error_log

for each command have "Permission Denied"