elsabiet wrote:
Can I turn off synch for my Mac, then delete some photos, and still be able to find them in iCloud?
What happen if I turn on Synch again for my computer - it is going to update the photo library by deleting the ones that are not on the mac anymore?
This will work for a limited time, but it is risky. You have to be very sure, that iCloud Photos has been disabled on your Mac, before you start deleting photos. While iCloud syncing has been disabled, you can access the photos on the web page www.icloud.com .
When you enable iCloud syncing again, the deleted photos will sync back from icloud to your Mac. But it will create a lot of unneccesary network traffic. First, your Photos Library with the remaining photos will upload to iCloud and be merged into the existing iCloud Photos Library. Then the merged library will be downloaded from iCloud to your Mac.
if you need currently more storage on your Mac I would simply move your Photos Library to an external volume to keep it safe, then delete the library on your system volume. Once you do no longer need the local storage, create a new, empty Photos Library and make it again your iCloud Photos Library. The iCloud Library will download to your mac and you will save the lengthy new upload to iCloud.