Resetting the Kindle will wipe off everything. I don't think that is what you want to do. Which Kindle model is it? Is the device a Kindle eInk or a Kindle Fire? I'm thinking you only want to have her be able to view books that have been downloaded to the Kindle. You seem to want to hide books that are in the Kindle cloud, that is, located in the Amazon servers. Depending on which Kindle you have, you need to set the Kindle to show only Downloaded books. Then you need to turn OFF the WiFi so the Kindle cannot connect to the cloud storage. Additionally, you might want to use the Parental Controls to restrict her from accessing the server (cloud). I've never used the parental controls, so perhaps someone who has can better explain them.