Easy way to permanently delete all photos and videos from iPad/iPhone
If you wish to "keep" the videos or pictures and also clear your iDevice, make sure you sync or backup your pictures in any way you choose before deleting.
The EASIEST way to delete All pictures and/videos is to attach your device to a MAC with an USB cord. Start the app "Image Capture" and select all content you wish to delete. Once selected, there is a delete function inside of image capture, choose this and all selected content on your iDevice will be deleted.