Once the lending period for a Kindle Book ends, it will expire and automatically return to the library (you can also return it early so someone else can check it out; see link below). Expired Kindle Books still appear on your Kindle device or reading app but can't be opened. You can remove them from your Kindle device or reading app using these steps:

1. On Amazon's website, navigate to Account and Lists under your profile, then click Content Library.
   
   
2. Choose Books.
   
   
3. Click Deliver or Remove from Device from the right hand menu next to the title.
   
   
4. Uncheck the checked box for every device from which you want to remove the title.
5. Click Make Changes.

This will permanently delete the book from your Kindle device or reading app the next time you sync.