private void RemoveRolesFromUser(Guid idUser, IEnumerable <Guid> idRoles)
        {
            if (idRoles == null || !idRoles.Any())
            {
                return;
            }

            var roleArray = idRoles.ToArray();

            var roles = GetAssociatedRolesForUser(idUser, roleArray);

            if (roles.Any())
            {
                _service.Disassociate(SystemUser.EntityLogicalName, idUser, new Relationship(SystemUser.Schema.ManyToMany.systemuserroles_association.Name), new EntityReferenceCollection(roles));
            }
        }