If you go to Settings > Photos & Camera > turn "icloud Photo Library" to off > you should receive a prompt for two options. click "remove from iphone" the pictures should delete from iphone within 2-5min. If they don't open and close Photos to refresh the app.
once photos are deleted you can now turn "icloud Photo Library" back on and new photos you take will upload to your icloud and be added to your collection past.
This worked for me on iOS version 10.2 on an Iphone 5s
If your photos don't delete from your iphone after this you may need to delete them manually.
Ensure you have "icloud Photo Library" turned off when deleting from Iphone.
also Open www.icloud.com on a computer go to photos section to ensure while deleting photos from your iphone they are not disappearing from your Icloud. Refresh the webpage every now and then just to be safe.
I do not know how this effects photos in iphoto library on a Mac as I only use www.icloud.com to store pictures.
Hope this helps.