If you created your site under a sub-account as I did, and if you want your entire site taken down (i.e., don't need to manage individual files) and are still having problems, the below procedure should do the trick. Took about 3 minutes total to figure out on my own and remove my sites (it ain't rocket science):
1. Login to account.
2. On the toolbar at top, drill down to Account >> Account Profile >> your relevant profile (click on it).
3. In your profile, scroll down to sub accounts.
4. Click Manage Sub-account. You should now be in the Verizon/Yahoo Account & Billing page. Here is where you can manage/delete each sub account (including its associated Web Space) as desired.
5. After deletion, try accessing via browser the mysite.verizon.net/ URL you were using for your website. You should get a an error (423 locked). Your site is now down, permanently.
Once deleted, all files associated with that sub account/web space should be purged -- if not immediately, then the next time Verizon does its routine system house cleaning.
NB (duh): If you created your site using a different method (e.g., not a sub-account, extra $pace, business account), the above may not work for you, as Verizon may have stored your files on a different machine/server/location, which may require additional/other steps (or even their personal attention to your specific case).
