how do I remove books from my kindle after reading is completed?

Question

In my first kindle I was able (at the completion of reading) to send a book to a particular category and remove it from my "active" list.  Now, on my 2nd Kindle I cannot discover how to do that.  All my books, after I read them, continue to show up on my list of books.   I simply cannot remember if I've read some of them or not, and I'd like to remove those already completed to a list or remove them completely from the kindle, so that only unread books show on the list.  How do I do that?