Yes, if you'd like to change the account used for the Kindle or give the Kindle to another user, you'll first have to deregister the Kindle from the current account.
To deregister your Kindle:
1. From the Home screen, tap the Menu icon, and then tap Settings.
2. Tap My Account and then tap Deregister.
3. Tap Deregister again to confirm.
You can also deregister your registered Fire tablets, Kindle e-readers, or Kindle reading apps online from Manage Your Content and Devices : www.amazon.co.uk/mycd
Hello Forum people, My name is Zach and I am a Moderator for Amazon. I enjoy Film Making, Graphic Design and Web Design in my free time (Different than Kindle Freetime of course). I am also an avid adventurer, looking forward to my next outing!
Might help to warn the users of Amazon Fires, that their device will be stripped of all Amazon content including game/app settings and game progress if they do that