Hello Noel See,
It may be beneficial for you to reach out to Esri Australia with this kind of question. They are your primary support provider and can assist in answering your question and any followup questions you might have. Esri Australia can reach out to us on your behalf if that should come to pass.
Per ESRI documentation you can specifically delete the geometric network and this will convert all the gemoetric network features into point and line features (instead of junction and edges). You can then selectively delete the feature classes you no longer need. For more detail, as Jason has already said, please consult with ESRI as this is all ESRI functionality.
- Terri Harris, ArcFM Support