I enabled iCloud Music Library and subscribed to Apple Music.
I have iPhone with 16 GB and wish to delete all local music files, to free up space for other stuff. Before iCloud Music I would "not sync" my music files and then they get deleted from iPhone.
With a search engine I found how to to delete songs in Music app. Bud sadly I need to delete every artist individually. I have about 600 different artists and albums.