If it's for debugging purposes, you can find your app in Settings -> Applications -> YourApp -> Storage -> Clear Data. That will remove everything you store in your app space including preferences and permissions. That way you can Run your code and have a fresh start. In older Android Versions you can find teh same screen by long pressing the app icon and selecting App info. If you want the same thing to happen at runtime with your users, you can manually clear the data each time your app is closed by using the following code:
((ActivityManager)context.getSystemService(ACTIVITY_SERVICE)).clearApplicationUserData();
(This requires a min sdk of 19). If your min target is older than 19, there areother way to do it as well. Check this answer.