Hi, thanks for using JustAnswer.com I am Cris.
If you have lost your device you can deregister it from your account. Use the link below to sign into your Amazon and once your logged in deregister the Kindle. It will remove it from your account so no one can order on the Kindle from your account.
Once you reach the page log in then click on the Device tab. Click on the Kindle and you will see a de-register option.
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