In order for you to download any applications, books, or audiobooks, your Kindle e-reader must be synced to your Amazon account — and, therefore, so must any credit or debit card information that you have registered. If your Kindle ends up lost or stolen, the first step that you should take is to deregister your Kindle to ensure that no one who may gain access to your e-reader can make unauthorized purchases with your information. You might also want to deregister your device in order to assign a different Amazon account to it.
This tutorial will walk you through the two ways that you can deregister your Kindle.
Deregister a Kindle on a Computer
In order to begin, you need first to log in to your Amazon account.
Hover over Your Account. Scroll to and select Manage Your Content and Devices:
Click Your Devices > Deregister. In the dialog box that pops up, confirm that you want to finish the process by clicking Deregister again:
Deregister a Kindle from Your Device
You can also deregister a Kindle using the device itself.
From the home screen, simply go to Menu > Settings, and click Deregister.