I go to photos app.
I DO NOT select "Delete after import" (for the purpose of seeing if it mattered). I import photos from iphone.
Now I havent found an obvious way to go back and delete all of the just imported photos from my device.
If anyone has a way to do this that would be good.
If you do not want to deal with this, select "delete after import" when you are importing photos. This is for if you forget to do that.
Easiest way is to use Image Capture from OS X
You can use it to Import too, to any app that can import pictures, or to a folder location.
Select any pictures you wish to delete & hit the 'no entry' sign to trash from your device
Here's a way I found to do it. In Photos on the Mac, click the device in the sidebar so all the photos are displayed. Scroll to the top and there should be a section called 'Already Imported (xx items)'. Click 'Show all', then select the photos you want to delete. Ensure the 'Delete Items After Import' box is checked. Hit 'Import Selected' and wait for them to be imported. Now you'll have duplicates of those pics because they were already imported. Just go to the 'Last Import' Album and delete all those pics you just imported. Then if you want you can go to 'Recently Deleted' and bin them for good.
It's a bit of a convoluted solution but it works if you have a whole stack of random 'already imported' photos on your device and just want to delete them reasonably quickly.
I also had the same problem that the "Delete after imports" option in Photos seemed to have disappeared.
The key thing to bring it back was to UNLOCK your phone BEFORE connecting the USB. If the phone is unlocked and THEN connected, the option "delete items after import" appeared.
