You’ll have to write some sort of cronjob (or WP Cron)
you could base this on the getting and deleting orders functions here
https://docs.wp-pizza.com/developers/?section=function-wppizza_get_orders
or of course use WP_Query itself or even your own sql statement

essentially you need to query the [yourprefix]_wppizza_orders table by orde_date and delete the entries as you require
be aware that every order id in that table might also have associated metadata in [yourprefix]_wppizza_orders_meta
so you will want to get those too and delete the rows in that table as well or you will end up with orphaned entries in the meta table.

alternatively – if you are really quite sure you want to delete all entries, simply truncate those 2 tables at whatever time is appropriate