In the Manage Your Content and Devices section, go to the bottom of the page. Select your device or app from the drop-down menu. Deregister it by selecting Deregister on the pop-up window that appears. Confirm by choosing Deregister again on the pop-up window.
Go to Manage Your Content and Devices, sign in to your account, and select the device you want to delete. Select your device from the drop-down menu, click Deregister, then confirm by clicking OK.
