How do you remove UNIQUE items from a column and retain DUPLICATES?

I apologize, I wasn't specific.
I have 10 columns of data. Only Colum A contains unique and duplicate data. I want to delete, not seperate or extract, the unique data (and the following colums) for each row containing unique data in column A.

Try this:-

Sub MG21Feb31
Dim Rng     As Range
Dim Dn      As Range
'Change below to "A2" if data starts on row 2.
Set Rng = Range(Range("A1"), Range("A" & Rows.Count).End(xlUp))
With CreateObject("scripting.dictionary")
.CompareMode = vbTextCompare
For Each Dn In Rng
    If Not .Exists(Dn.Value) Then
        .Add Dn.Value, Dn
    Else
        .Remove (Dn.Value)
    End If
Next
Dim k
For Each k In .Keys
    .Item(k).EntireRow.Delete
Next k
End With
End Sub

Regards Mick