Deleting pics
How can I delete photos from my phone but keep them saved in icloud
iPhone 12 mini, iOS 17
Question marked as
You don't. iCloud is a syncing service to match the photos on your device to those in iCloud, it is not for external storage. Optimized storage will help with space on your device by only storing lower quality versions on the photos on your device and download the full version when needed.
You can shut off syncing iCloud on your device to delete photos without them being removed from iCloud, but you would need to have another device with the same Apple ID that is syncing photos to iCloud. Otherwise your photos will be deleted in iCloud after 30 days if there is no device using the service to sync the photos.