Downloaded and loaned ebooks expire automatically at the end of a loan, and cannot be returned early. Deleting the ebook file from Adobe Digital Editions deletes the ebook file from your device, but does not end the loan.  
Downloaded and loaned ebooks appear in your Ebook Central Bookshelf, in the “Downloads and Loans” folder, for the duration of the loan or download period. The time remaining in your loan is displayed in orange.
Ebook Central Bookshelf, downloads and loans folder, displays the time remaining in a download or loan. This ebook has 1 hour remaining in the loan.