Originally Posted by
dpscott This should auto remove them from your phone whilst keeping them in iCloud.
No! It doesn't delete them from the phone. You will still see them in your camera roll and respective albums, if this was already the case.
The only difference will be that the actual photos will be replaced by thumbnails, thus taking less space. In order to view the photos in full resolution you will have to be on wifi or cellular data.
Here is a blog about iCloud Photo Library from iMore:
http://m.imore.com/how-free-space-yo...-photo-library
Secondly... if photos are that important you should be backing them up elsewhere anyway.
Good advice.