How to delete all photos from the iOS 7 camera roll WITHOUT importing them?
On iOS 7


Open the Photos App and make sure you are in the “Photos” section from the three icons at the bottom of the screen;
Look at the top of the screen and make sure the view is “Moments;”
Now you can tap individual thumbnails one at a time to select them, or you can tap the word “Select” that appears at the top of each grouping to select an entire grouping.




On iOS 6


Go to Settings → General → Usage → Photos &amp; Camera;
Swipe on the “Camera Roll” entry;
A “Delete” button appears.


This solution does not work on iOS 7 (last tested on iOS 7.0.4). It is probably a bug.



Any iOS, but using a computer

If you have iOS 7, you can use Image Capture on your Mac to delete photos from the iPhone without importing them:


Plug the iPhone to your Mac with the iPhone cable;
Quit iPhoto if it launches automatically;
Launch Image Capture;
Select the photos you want to delete;
Click the red icon to delete the photos.