This will delete every even-numbered row starting with row 2.

Sub delete_even_rows()
  Dim r As Long
  Dim Rng As Range
  Dim numLoops As Long

  Set Rng = [A1:A2000]
''or 1000 if that is total rows
  numLoops = Int((Rng.Rows.Count / 2))
  For r = 1 To numLoops
    Rng(r + 1, 1).EntireRow.Delete
''change r + 1 to r + 2 for odd rows
  Next
End Sub

Gord Dibben  Excel MVP - XL97 SR2

Insert a column.
Enter into top cell =Mod(1+Row(),2)
  (or =Mod(Row(),2) to delete odd rows).
Fill to row 2000.
AutoFilter the column on 1.
Select top cell. Hold Shift, press End, then Down.
Right-click Selection.
Choose Delete Row.
Delete Column.