This will do the trick, if the column you want is the farthest left and is sorted.
Sub delete_duplicates()
rowx = 1
Do Until Cells(rowx + 1, 1).Value = ""
If UCase(Cells(rowx, 1).Value) = UCase(Cells(rowx + 1, 1).Value) Then
Cells(rowx + 1, 1).EntireRow.Delete
Else
rowx = rowx + 1
End If
Loop
End Sub
Takes a little while. But I did one with 16,000 rows last Friday - and it took about 4 minutes to run. Far better than by hand, though.