If the playlist appears under 'Recent' on your page then yes, it will disappear after a while, as it only shows the most recent 5 playlists. However, if you've SAVED a playlist, there doesn't seem to be a way to delete a folder or to edit folder titles. The only option seems to be to remove a saved playlist from a folder (or "shelf") by clicking on the playlist, then clicking on the 'Save Playlist' button again and deselecting the playlist it was saved it to. Hope this gets addressed!
I agree.. we should be able to edit our playlists. I have a saved playlist for mornings and dont like all the playlists anymore. i would like to get rid of them? should be so easy to put a delete..edit button in that catagory