photos mac and iCloud

Photos and iCloud are connected whilst online. If you delete a photograph from the Application [Photos] they will be deleted from iCloud on all devices, as soon as you are connected online. A message will appear that warns 'Delete from all your devices? This item will be deleted from iCloud Photos on all your devices.' If you make this choice the photograph will be 'deleted' However it will remain in your Recently Deleted file within your Library for about a month. By looking in the Recently Deleted file you will see a countdown marker on each photograph that reduces one day at a time. At any time until the day the a deleted photograph expiry date reaches you can restore it back to your Photos library by selecting it [right click] and choosing Restore. If you delete it again the countdown will resume from around 30 days. If you delete any photograph from the Recently Deleted file it will be permanently deleted from iCloud. If you are unsure about this process try taking a random photograph which doesn't mean anything to you and try this delete process to test the procedure.

Have you tried looking at Preferences in the drop down menu of Photos then selecting the iCloud icon. Here you can choose to Optimise Mac Storage keeping the full resolution versions in iCloud. Vince