JS Bridge Resco Unrequiring a field on the form

 MobileCRM.UI.EntityForm.requestObject(
                    function (entityForm) {
                        var detailView = entityForm.getDetailView("Summary");
                        var item = detailView.getItemByName("parentcontactid");
                        item.validate = false;
                    },
                    MobileCRM.bridge.alert,
                    null
                );