When you choose to make an offline playlist only available online again, does it automatically remove the music files it had to download on the mobile?  

I've recently found I'm running out of space on my mobile and about 2/3 of my space is taken up by music (the only music I've got on my phone will be from Spotify) but when I go into the folder, I can't tell what songs they are as the naming convention is not what I expected (random letters and numbers rather than the name of the song).

I can't go and delete any of those folders without knowing if they are part of a playlist I would like to keep offline and I'd rather ask the question to the community before needing to go through and turn off all offline playlists on my mobile just to find out the answer!