[Solved] Remove file older than 90 days

Shell Programming and Scripting
1

I have crontab job a tar file to a directory ( tar -cvf /tmp/backup/or.`date +%m%d%y`. /ora/db/* ) , it will do it every day . Now I don't want to keep too much files , I just want to keep the file for 90 days , can advise if I want to remove the backup file which are elder than 90 days , can advise what can I do ?
Thanks

2 
# find /tmp/backup -type f -mtime +90 -name "*.tar" -exec rm {} \;

Cheers,