Unfortunately, apps can sometimes be problematic. Depending on the app, it could even become incompatible with other apps, or the OS of your device. The best way to resolve this is to uninstall the app. In order to uninstall the app, open the App Drawer (6 White Dots), press and hold the app you wish to uninstall, and drag it to the UNINSTALL button at the top right of the screen. Alternately, you can select the uninstall button from the app menu.