code: def unfollow(ctx, nick):
      
      source = ctx.obj['conf'].get_source_by_nick(nick)
  
      try:
          with Cache.discover() as cache:
              cache.remove_tweets(source.url)
      except OSError as e:
          logger.debug(e)
  
      ret_val = ctx.obj['conf'].remove_source_by_nick(nick)
      if ret_val:
          click.echo("✓ You’ve unfollowed {0}.".format(
              click.style(source.nick, bold=True)))
      else:
          click.echo("✗ You’re not following {0}.".format(
              click.style(nick, bold=True)))
docs: Remove an existing source from your followings.