why would you want to delete the playlist...playlists are like videos you upload to your channel. The have their own unique link and youtube looks at them as a new content on your channel. deleting them will be like deleting videos that have generated views to your channel...my advice just keep building more playlist and you will see how it help your channel grow.At what point do you think it makes sense to delete these playlists? Over time they can really accumulate lol