How do I delete iCloud photos from iPhoto on Mac without deleting the photos from iCloud

To save storage on your Mac you can enable the "Optimise Mac Storage" option in the Photos Preferences > iCloud. Then Photos will automatically remove some of the full resolution originals from your Mac and keep them only in iCloud.

Or move the complete Photos Library from the Pictures folder to an external volume.

Move your Photos library to save space on your Mac - Apple Support

When you simply delete the complete Photos Library from your Mac, the photos will stay in iCloud.

You can then create a new, empty Photos Library that is not syncing with iCloud, if you want to use Photos on your Mac.

I want to remove all photos from my mac without deleting them from my iCloud.

Using the iCloud Photo Library, this is not possible. It is a syncing service, not off device storage.

You can move your library to an external drive to get it off your Mac.

See >>> https://support.apple.com/en-us/HT201517

How do I delete iCloud photos from iPhoto on my Mac without deleting the photos from iCloud

iPhoto or Photos? They are not the same application.

iCloud is a syncing service, not off device storage. Photos are synced between subscribed devices. They must reside on your Mac as well as on iCloud.