Snort Log retention

If your organization has a log retention policy, then the duration of retention should be documented. If your organization comes under the auspices of some regulatory body or document - Sarbanes-Oxley, for example - then this may mandate a retention period for certain types of transactions. If the log data isn't covered by either of these and you don't need it for any other purpose - like later investigation or audit - then I see no reason why it cannot be deleted.