Assumptions
1. The values to be deleted are in column B
2. every column that has some data, has a column header
3. The master list is in column A
Sub UnMatchedListSecond()
Dim lMaxRows As Long 'max rows in list 2
Dim iMaxColumn As Integer 'last column on row 1 with no header. to be used for calcultion
Dim lThisRow As Long ' a temp row counter
''last column on row 1 with no header. to be used for calcultion
iMaxColumn = Cells(1, Columns.Count).End(xlToLeft).Column + 1
'max rows in list 2
lMaxRows = Cells(Rows.Count, "B").End(xlUp).Row
Cells(1, iMaxColumn) = "NEW VALUE"
Cells(2, iMaxColumn).Select
ActiveCell.Formula = "=COUNTIF(A:A,""="" & B2)"
Cells(2, iMaxColumn).Select
Selection.AutoFill Destination:=Range(Cells(2, iMaxColumn), Cells(lMaxRows, iMaxColumn)), Type:=xlFillDefault
Selection.Copy
Selection.PasteSpecial Paste:=xlPasteValues
For lThisRow = lMaxRows To 2 Step -1
If (Cells(lThisRow, iMaxColumn) > 0) Then
Cells(lThisRow, "B").Delete Shift:=xlUp
End If
Next lThisRow
Range(Cells(1, iMaxColumn), Cells(lMaxRows, iMaxColumn)).Clear
End Sub