Hello Geoffrey! Thank you for your question. I will be assisting you today.I'm sorry about the issue. To delete all books at once, you can go to the menu/setting on the kindle, and look for the account or registration and deregister, then re-register. Or reset the kindle to factory defaults.If you cannot find these options, please let me know the model of your kindle.
When you are available, please click on the Reply to Expert tab below, and reply back to me, so we can continue. Thank you.