A friend of mine secured his OneDrive app on Windows Phone 8.1 with a pin number but can't remember it. As the app is part of the OS it can't be reinstalled from the store. Is there another way to fix this than do a hard reset?
When you put in 4 times the wrong pin you have to reconnect to the app using your Microsoft Account & password. Then the app will ask you if you want to use a pin or not. If you still want to use one just type in a new one (twice) and confirm.