Public Sub test()
    Dim x As Document
    
    ActiveDocument.SaveAs "e:\temp\test.docm" ' please don't mind this, it is just here for testing
    Set x = Documents.Open("e:\temp\test.docm") ' this also
    ' imagine I want to everything before Page 3 and after Page 5
    DeleteBefore x, 3
    DeleteAfter x, 2
    x.Save
End Sub


Public Sub DeleteBefore(ByRef doc As Document, ByVal page_num As Long)
    Dim Rng As Range
    If page_num <= 1 Then _
        Exit Sub
    With doc
        Set Rng = .GoTo(wdGoToPage, , , 1)
        Set Rng = Rng.GoTo(wdGoToPage, , , page_num)
        Rng.Delete
    End With
End Sub

Public Sub DeleteAfter(ByRef doc As Document, ByVal page_num As Long)
    Dim Rng      As Range
    Dim max_page As Long
    max_page = doc.Content.ComputeStatistics(wdStatisticPages)
    If page_num >= max_page Then _
        Exit Sub
    With doc
        Set Rng = .GoTo(wdGoToPage, , , page_num + 1)
        Set Rng = Rng.GoTo(wdGoToPage, , , max_page)
        Rng.Delete
    End With
End Sub