@j.stewartwallace,

If you can't figure it out email us and I'll take care of it for you. To manage it yourself, just visit the vocabulary page:

http://popupchinese.com/vocabulary

There will be a select option in the right-hand sidebar. Select the option "edit page length" and pick a large number like 1000. Then when the page reloads, use the same select option to pick "select all" and then "delete checked".