Recycle bin is a new function added after WordPress is upgraded to 2.9. When an item (log, comment, etc.) is deleted, it is not permanently deleted. Instead, it is stored in the recycle bin. If the deletion is wrong, it can be recovered. But sometimes, when you really think that it is unnecessary to keep the deleted items, you need to empty the recycle bin manually. It’s troublesome. Here’s a trick to specify WordPress to empty the garbage bin automatically every fixed number of days.
Open your WordPress root, WP- config.php File and paste the following code:
define('EMPTY_TRASH_DAYS', 10 );
The number 10 above stands for 10 days. When the number is set to 0, the recycle bin function is disabled.