Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble, Jewel.
You need to touch and hold on each individual title, then it will bring up an options menu, and you can choose Remove or Archive, to take them off the tablet app.
You generally don't want to delete on the amazon site, because that permanently removes the book from your account, and if you ever wanted it again you'd have to purchase it again. By doing the remove or archive, that keeps it available in the cloud to download later if you wish, but doesn't take up space on your device. If an item shows on your app as being in the Cloud library (not the Device library) then it is not stored locally on your tablet.
Did you need more help with this?