I have plenty of kindle books in my kindle 5, that were directly imported. Either by calibre, or just sending .mobi files to @kindle.com. How do I delete those? Honestly, I would like to erase all my kindle data and redownload all the books that are sync'ed with my amazon account. I tried doing factory reset, but once I connect kindle to my account, all the books are restored as archived items...and deleting them by hand is not an option. In other words I want my kindle device to have only the books that I bought. Any suggestions?
It might be easier to go to the Manage Content page, select Your Devices tab, put a check in the box for the device you want, then in the popup look for the option, View Device Content.
Doing that should let you do a mass deletion of items on a device without having to worry about deleting it on the cloud. By the way, for my account, it looks like View Device Content has two listings for each device: one for audio recordings, another for ebooks. You will see the View Device Content option only in one of those two listings. This should do it.