From version 2.9 of WordPress you have a Recycle Bin for articles. Definitely a step forward that brings in the dimension of the WordPress as CMS. Trash is emptied automatically every 30 days, but if you want change this you can do a little touch to the wp-config.php file present in your web root.

Add the line:
define( 'EMPTY_TRASH_DAYS', 15 );
where the value 15 are the days that pass from the time when an article ends up in the trash when it is finally eliminated.
And if we want to completely disable the trash? We do this by inserting the value zero