This wp-config.php function controls the days before WordPress permanently deletes posts, pages, attachments & comments from the trash bin.
This function will automate the process of deleting WordPress Trash & you will not have to press the ‘Empty Trash’ button again for your installation.
Default WordPress Trash Settings:
The default is 30 days.
define( 'EMPTY_TRASH_DAYS', 30 ); // 30 days default