I have gobs of photos in iCloud, automatically uploaded from two different phones. Most/all of them are redundant, as I've also imported them into Photos on my Mac. I need the iCloud space to back up those phones. I feel certain it should be possible to mount the iCloud storage as a virtual drive from my Mac, or access my iCloud photo storage from Photos, so that I can check the photos are duplicates and delete them, or download any I don't already have on the computer — and delete them.
But the photos don't appear under iCloud in Finder. I tried enabling Photos under iCloud in Settings, thinking that might let the iCloud photos show up in Photos, but evidently that tries to sync my local photo library up to iCloud, which of course fails because iCloud is full.
I've read I should be able to access the photos by going to icloud.com with a browser, but that doesn't seem to be working, either.
I know I could pay to get more iCloud storage, but I don't want to do that, because I have no desire or need to keep all those photos in iCloud anyway.
Update: Maybe I'm going about this the wrong way. I eventually managed to get in to iCloud.com, and I see that if I delete photos there, it's also going to insist on deleting them from all devices, which is not what I want. I guess I have to tell my phones to stop synching photos to iCloud, and then maybe worry about expediting their deletion from iCloud. [But I'm having trouble doing that, too.]