WordPress Themes Development Question:

First, unchecked Allow link notifications from other Weblogs (pingbacks and trackbacks.) on the Options > Discussion panel. This will only disable trackbacks and pingbacks on future posts. Now, to completely disable trackbacks and pingbacks, you will have to edit each past post and uncheck Allow Pings from the Write Post SubPanel. Alternatively, run this MySQL query from the command line on a shell account or using PHPMyAdmin: UPDATE wp_posts SET ping_status=”closed”;
If your goal is to permanently disable trackbacks and pingbacks, then you should delete the wp-trackback.php file as well.