iphonephotosstorage
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.
Aperture does not seem to offer this functionality for the iPhone. So after importing it does not give you the option.
See picture here: Aperture Import finished
But after importing you can always use Image Capture to delete the photos in one go:
See picture here: Image Capture
I'd go for the 'not quite cave-man' approach - though still a bit manual...
Launch Image Capture.
Plug in iDevice
Select any/all photos you wish to delete
The Delete button is at the bottom of the window [the 'no-entry' sign]
After comments - the button is still there in Yosemite.
Update Nov 2015 - the button is still there in El Capitan, though it is now black & white, not red.
Picture updated to Image Capture 6.7 after further queries on the button not being there.
Update July 2016, as people are still missing this bit...
Best Answer
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