code: def deregister(cls, attr_name):
          
          try:
              field = cls.get_field_by_fieldname(attr_name)
          except InvalidField:
              raise ValueError("'%s' is not registered" % attr_name)
          if not isinstance(field, ExtendedPropertyField):
              raise ValueError("'%s' is not registered as an ExtendedProperty" % attr_name)
          cls.remove_field(field)
docs: De-register an extended property that has been registered with register()