Delete old files

remove.sh

#!/bin/bash
FILE=/xxx/xxx
find ${FILE} -ctime +5 -type f -exec rm -f {} \;

Change the permission.

# chmod +x remove.sh
# crontab -e

Register it as cron job.

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/
1 20 * * * root /root/remove.sh

Done.