list.FindAll

List<ColumnProperty> new_columns = columns.FindAll(delegate(ColumnProperty p)
                {
                    if (p.Name != "RowStamp")
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                });

========================================

public void Test_Find()
        {
            List<PersonInfo> Pers = userinfo().FindAll(delegate(PersonInfo p)
            {
                if (p.userid == "31")
                {
                    return true;
                }
                else
                {
                    return false;
                }
            });

            string s = string.Empty;
            if (Pers.Count > 0)
            {
                s = Pers[0].userName.ToString();
            }

            string b = s;

        }

        public List<PersonInfo> userinfo()
        {
            List<PersonInfo> Per = new List<PersonInfo>();
          
            for (int i = 0; i < 4; i++)
            {
                 PersonInfo p = new PersonInfo();
                 p.userid = i.ToString();
                 p.userName = "Tsj_" + i.ToString();
                 Per.Add(p);
               
            }
            
            return Per;
        }
    }

    public class  PersonInfo
    {
       
           public string userid = string.Empty;
           public string userName = string.Empty;
       
    }