code: def delete(self, username, realm=None):
          
          if realm is None:
              # This case makes the username optional, so
              # the full name can be passed in as realm.
              # Assume it's already encoded.
              name = username
          else:
              # Encode each component separately
              name = UrlEncoded(realm, encode_slash=True) + ":" + UrlEncoded(username, encode_slash=True)
  
          # Append the : expected at the end of the name
          if name[-1] is not ":":
              name = name + ":"
          return Collection.delete(self, name)
docs: Delete a storage password by username and/or realm.
  
          The identifier can be passed in through the username parameter as
          <username> or <realm>:<username>, but the preferred way is by
          passing in the username and realm parameters.
  
          :param username: The username for the credentials, or <realm>:<username> if the realm parameter is omitted.
          :type name: ``string``
          :param realm: The credential realm. (optional)
          :type name: ``string``
          :return: The `StoragePassword` collection.
          :rtype: ``self``