First, you have to sort all the records with respect to column A.
then run this vba code to remove all the duplicates.

Sub RemoveDuplicate()

totalrows = ActiveSheet.UsedRange.Rows.Count
For Row = totalrows To 2 Step -1
If Cells(Row, 1).Value = Cells(Row - 1, 1).Value Then
Rows(Row).Delete
End If
Next Row

End Sub