Delete/hide duplicate rows

Sub test()
Dim LastRow As Long, DataRng As Range, ChkRng As Range

'finds the last used row on the sheet
LastRow = Cells.Find("*", after:=Range("A1"), searchdirection:=xlPrevious).Row

'range of data (assuming row 1 is a column header and data starts in row 2)
Set DataRng = Range("A1:I" & LastRow)

'column J will be used to mark the duplicates
Set ChkRng = Range("J1:J" & LastRow)

'use advanced filter to show only unique entries
DataRng.AdvancedFilter Action:=xlFilterInPlace, Unique:=True

'mark the visible rows with an 'x' in column J
ChkRng.SpecialCells(xlCellTypeVisible).Value = "x"

'remove filter
On Error Resume Next
ActiveSheet.ShowAllData

'delete any rows that do not have an 'x' (the duplicates) in column J
ChkRng.SpecialCells(xlCellTypeBlanks).EntireRow.Delete
On Error GoTo 0

'delete any data in column J
ChkRng.ClearContents

End Sub