[WP8] How do you get songs to delete off of the phone when taken off of offline mode?

[Kevanian]

I have the Nokia Lumia 920, and I've made numerous playlists available in offline mode.  I took up my entire phone space.  I turned a few of the larger ones off to get more space but I can't get the space back eventhough those lists are now only available online. Is there something I'm missing?

[DryMarker]

If the phone is close to running out of storage space then Spotify will clean up after itself and delete the unwanted tracks.

Copy a few big files onto the phone, then run Spotify, then delete the big files again.