Hi Rich,
Your "sent" pm's also count. So - if you go to:
http://parkerguns.org/forums/private.php
And select: "Sent Items" (just under the colored bar graph near the top of the page) - you can delete your "Sent Items" as well...
If you want to save them to your computer before deleting them - you can do that as well...
Near the bottom of the page - look for:
Download all Private Messages as:
XML | CSV | Text
John