How to delete all photos in iOS8 iPhone with Mac

I have searched this board and not found an answer. Then I figured one out and so I am posting.

I have iPhone 6 with iOS and use Photos on Mac and iPhone. I don't always select "delete after import" when I upload to the mac (via cable), and ended up with thousands of photos on my iPhone. These are already on my mac, but I want to get rid of them on the iPhone. I had not been able to find a bulk way to delete them. I have already undone "synch photos" in iTunes to get rid of ones that are under control of iTunes.

I found a solution: Using Image Capture, I retransferred the photos on the iPhone to the mac into a separate folder (not sending duplicates into Photos,but keeping them double safe) and used the "delete after import" with the Image Capture program. Delete after Import is hidden in a little dialog under a down arrow in the bottom left of Image Capture.

If you don't know you have this program, do command-space bar to get searchlight, and type in "image capture".