Logging Out of a Lost Device
If you've lost your mobile device, you should update all registered security settings including password, mobile number, email address, and 2-step verification mobile number using a different device.
Changing your password will sign you out of Amazon apps and websites on any non-Kindle device. Updating your mobile number and email will prevent anyone else from accessing your account. Go to Change Your Account Settings for instructions.
Note: If you've lost your Kindle device, see Report Your Amazon Device as Lost or Stolen.