Staff can empty the whole blog for you. That will remove all data including posts, pages, tags, categories, comments, and uploaded files and once deleted, the data cannot be recovered.
If you are sure you want Staff to proceed, and you are prepared to wait then type modlook into the tags in the sidebar of this thread for Staff attention, and post here again to:
(1) confirm the URL of the blog you want them to empty;
(2) confirm that you know content deletion is irreversible.