There was a thread about this, but it's from 2013 and not tagged as a request. I still don't see this as an option on the site, so I have to assume it was unresolved back then.
Pony.fm playlists have a noticeable lack of a "remove" button if you accidentally add duplicates, add the wrong song, find a more updated version, etc. Any of the reasons you might want to edit a playlist.
Is there a more complex issue behind this? If it is at all possible, I would really appreciate the time to look into adding one. Thank you!