LIst collection item not removes

Suppose I have two list likes..
List list1={1,2,3,4,5};
List list2={2,3,4};
now i want result in third list like..
List list3={1,5};

I have use

foreach (var t in purchaseResult)
                {
                    for (int counter = 0; counter < poRecive.Count; counter++)
                    {
                        if (t.RecNo == poRecive[counter].RecNo)
                        {
                            poRecive.Remove(t);
                        }
                    }
                }

but this code not removes data....