public void RemoveUserFromGroup(UserObject user)
        {
            if (user == null)
            {
                return;
            }
            if (string.IsNullOrEmpty(user.UserName))
            {
                return;
            }
            if (string.IsNullOrEmpty(user.GroupName))
            {
                return;
            }
            try
            {
                SPUser sharepointUser = GetUserObject(user.UserName);
                if (sharepointUser == null)
                {
                    return;
                }
                SPGroup sharepointGroup = GetGroupObject(user.GroupName);
                if (sharepointGroup == null)
                {
                    return;
                }

                sharepointGroup.RemoveUser(sharepointUser);
                sharepointGroup.Update();
            }
            catch (Exception ex)
            {
                var log = new AppEventLog(AppException.ExceptionMessage(ex, "RemoveUserFromGroup", "ClsHelper"));
                log.WriteToLog();
            }
        }