Did you also import music from iTunes or your MP3 collection, and now have hundreds of Spotify playlists you don’t want? It was driving me crazy, and I couldn’t find an easy way of deleting several playlists at once, so I built this program using libspotify-sharp by Jonas Larsson (thank you Jonas, you’re awesome!).
You simply enter how many playlists you want to keep (from the the top), and the program will delete all playlists below this number. So just move all your important playlists to the top, and run this program. It will not allow you to delete the top 30 playlists (as a precaution for complete fuckups) and you need to enter your Spotify username and password.
You need to be a paying Spotify customer. Sorry, no way around this.
If you get log messages about the playlist, exit Spotify and try again.
Update October 2011: Warning! If you use the new Playlist Folders (multiple playlists in one folder) the program doesn’t work very well. Make sure you temporarily move out all playlists of the folders and remove them before running this program. Some people have also reported the program doesn’t work in 64 bit, but it’s working fine for me (Win 7 64bit).
Disclaimer: It worked fine for me, and deleted over 500 playlists in the correct order, but use it at your own risk. Only delete a few at a time for example. You can also contact me if you want the source code.