code: function (identifierUrn) {
      if (identifierUrn) {
        var path = this.constructPath(constants.IDENTIFIERS, identifierUrn);
        return this.Core.DELETE(path);
      } else {
        return this.rejectRequest('Bad request: An identifier URN is required.');
      }
    }
docs: Delete an identifier
  @param  {String|Integer} identifierUrn A Robin identifier URN
  @return {Function}                     A Promise