Books not deleting on kindle fire

[Cthulhu4u]

Hi,

I have the new-ish Kindle fire, the one for $49 that OS 5 on it. Anyway, I can sideload my azw3 files just fine and they open and all is well. However, when I am done with one I select it and delete it goes away, but the file does not get erased from my books directory and when go back into my library it is there again. These are side-loaded books and aren't on the cloud. I can use a file manager to go into the actual book directory and delete it, but shouldn't the OS/app be doing that for me. If tried putting my books in the "Kindle", "Books" and "Documents" folders. They show up in my library from any of those directories, but don't get deleted from any of them unless I go in an manually do it.