Tab/hold the app (no matter where or what screen the app is located) and the screen images should shrink revealing the uninstall (Top Left) or Delete (Top Right). While tab/holding the app.. Drag to the desired options/location. Poof gone..
Welcome to Android Central! Flipboard is a preinstalled app, which means you can't uninstall it. You might be able to Disable it (which means it never opens, and never gets updated) in the App Manager, but not all preinstalled apps can be disabled either. This is what most people call bloatware. You'd have to root the phone to remove bloatware.