Do deleted iPhone photos remain in the iCloud Can I delete photos from my iPhone without losing the iCloud copies?

I am short of memory on my phone and want to free up space.
Deleting photos on your phone WILL delete the iCloud copy.

Instead open Settings > iCloud > photos and check the option "optimize iPhone storage".  This is supposed to allow the phone to have smaller photo files, while the original resolution is maintained in the iCloud copy.