1. Press the Delete Pages button (Delete Pages tool button) on the Page Operations toolbar (View->Toolbars->Page Operations) or choose Pages->Rotate...
    Delete Pages options
  2. Choose the range of pages you wish to delete.
  3. You can restrict the deletion to even, odd or even & odd pages.
  4. There is no undo for this operation. Please make sure you have a backup of the PDF before proceeding.