photos

iCloud Photos is a syncing service. Any photo you delete from a device where iCloud Photos is turned on will also be deleted from iCloud and from any other device connected to iCloud Photos. You can potentially reduce the storage space required on a device by turning on Optimize Storage. See: https://support.apple.com/en-us/HT204264

Apple does not currently offer cloud-only storage for photos. If that is what you want or need, you may want to explore 3rd party options such as Google Photos or Dropbox.

Another way that photos may be on iCloud (if you don’t have iCloud Photo Library turned on) is via a backup of an iOS device. The only thing you can do with a backup is use it to restore a device or set up a new device. The contents of backups are not viewable at iCloud.com and if you delete a photo from a device it will not be included in future backups and will be lost.

There is a risky method of cleaning up your iphone and you need to know exactly what you are doing or you will lose photos / video. Read the whole post first, before trying this.

First 'make sure 'Optimise iPhone Storage' is turned on, in Settings/Photos.

Next, Turn off 'iCloud Photos'.

This will appear to remove all photos from your iPhone, but will leave behind any photos you have downloaded from iCloud.

Check to see how many photos remain.

If it's a reasonably small number( <1000), you can delete these copies.

**Warning** when you re-enable iCloud photos, these photos will be moved to the 'recently deleted' folder in icloud.

Next, enable iCloud photos on your iphone, and make sure 'optimize' iPhone Storage is set up in Settings/Photos.

Wait until your iCloud library is fully synced (shouldn't take too long as you'll only be downloading optimised versions of the photos).

Now, log into icloud.com on a PC or Mac - won't work from iphone, go to 'Photos' and look in the 'recently deleted' folder. You should find all the photos you deleted in there.

Select them all, choose 'recover' and they be placed back in your Photos Library and will start syncing to your iphone.

At the end of this, you should have an iphone with no local photos (so freeing up space) and all photos available via icloud.