Manage app permissions in Android Marshmallow so they can only access what you choose.
1 Open your device's Settings app. Under "Device," tap "Apps" to see your list of installed apps.
2 Tap the icon for the app you want to manage. On the app info page, find a list of current permissions assigned under "Permissions."
3 Tap "Permissions" to change permission settings. Toggle the button to the left to turn existing permissions 'off'. Toggle the button to the right to turn those permissions back 'on'.
4 Note: Some apps may not be fully functional if certain permissions are turned off. You can change these settings at any time.