Back in the kindle ecosystem

I was weak and got the kindle scribe.... but i got used to how clean and organized my library was with Kobo. How can i clean my kindle library and organize my library. I have books i dont want anymore and i am missing a ton.

And also the covers some appear and some are a generic picture with text. And according to me all my books are epubs but the kindle say they are word documents.... i am so confused.