Can't delete photos in Windows

I have connected my iPhone 6 to a PC running Windows 8.1 in order to free up storage space on the phone. I tried moving pictures from the phone to the PC, but I keep getting a permissions error message. I can copy pictures, but not move or delete them. I am pretty sure I was able to move photos when I had an iPhone 4 and iPhone 5, but I can't do it anymore

I cannot believe that Apple cannot get their stuff together and fix iCloud once and for all. Confusing features, confusing names: Camera Photos, Camera Roll, Photostream, iCloud Albums, multiple ways to backup, and different amounts of free storage in iCloud reported in different apps. This just feels so familiar, the iCloud/iTunes torture chamber--after so many years, Apple keeps bringing me here.