using System.Collections.Generic;
public static void Main()
var AList = new List<string>{"1", "2", "3", "4", "5"};
var BList = new List<string>{"4", "5"};
ModifyList(BList, ref AList);
public static void ModifyList(List<string> BList, ref List<string> AList)
AList.RemoveAll(ae => ae == be);