'Delete config, or partial config, for the domain.
:param domain_id: the domain in question
:param group: an optional specific group of options
:param option: an optional specific option within the group
If group and option are None, then the entire config for the domain
is deleted. If group is not None, then just that group of options will
be deleted. If group and option are both specified, then just that
option is deleted.
:raises keystone.exception.InvalidDomainConfig: when group/option
parameters specify an option we do not support or one that
does not exist in the original config.'

def delete_config(self, domain_id, group=None, option=None):

    self._assert_valid_group_and_option(group, option)
    if group:
        current_config = self._get_config_with_sensitive_info(domain_id)
        current_group = current_config.get(group)
        if (not current_group):
            msg = (_('group    %(group)s') % {'group': group})
            raise exception.DomainConfigNotFound(domain_id=domain_id, group_or_option=msg)
        if (option and (not current_group.get(option))):
            msg = (_('option    %(option)s    in    group    %(group)s') % {'group': group, 'option': option})
            raise exception.DomainConfigNotFound(domain_id=domain_id, group_or_option=msg)
    self.delete_config_options(domain_id, group, option)
    self.get_config_with_sensitive_info.invalidate(self, domain_id)
