When you decide to upgrade your Kindle device, you may want to give away or sell your old Kindle. If you do not properly remove your old Kindle device from your Amazon.com account, however, you run the risk of the new owner using your account without your knowledge or permission. This is especially problematic if you have one-click ordering enabled in your Amazon.com account. With just a few clicks you can unlink your old Kindle and deactivate it from your Amazon.com account.
Log in to your Amazon.com account from your computer.
Click "Your Account" at the top of the page.
Click "Manage Your Kindle" under the "Digital Content" category.
Click "Manage Your Devices" under "Your Kindle Account."
Click "Deregister" under "Actions" next to the Kindle device you are transferring. Click "Confirm" to confirm you wish to unlink your Kindle from your Amazon.com account.
Advise the recipient of your old Kindle to log in to his own Amazon.com account and click "Register a New Kindle." He will need to enter the serial number from the Kindle's settings menu and then click "Register."