I had a deleting problem also. On my Kindle two Audible items showed up( I really don't know where from) when I registred it: 1. your first read 2. Anna Karenina; a free audible book I got when I bought an iPod some years back (I went for the longest book).
I deleted them from my collection Audible -they went to Archived Items- and they're like bugs- I can't get rid of them.
Edit: excuse me, it's already been taken care of with the following steps:
Kindle displays the items you've downloaded on the Home screen. Kindle active content not on your Kindle will be available in your Archived Items. You can delete downloaded content from your Kindle. These items are saved within your Archived Items, and will be available for download again.
If you want to permanently remove a title from your Kindle account and Archived Items, please visit
http://www.amazon.com/myk and follow these instructions:
1. Locate the item you wish to delete in the "Your Orders" section. If you have a lot of content, you may need to use the Previous and Next links at the bottom to navigate through all of your content.
2. Click the "+" icon to reveal the order details and available actions.
3. Click on "Delete this title" button next to the title to permanently remove the title item from your account and Archived Items.