We are experiencing an error with the site currently where, sometimes, a topic/page cannot be removed by some posters. If you experience this error, please notify us. In the meantime, if you need to remove a mod-page but can’t, edit it and delete all the content in it (so it’s just an empty post), save it, and click delete to flag the page for removal; a moderator will remove it manually.
This only affects the page as a whole, not the actual mod files on the page. Those can still be removed by editing the post and deleting them.