You can update a schematic after features are removed from a network.

Click Bookmarks on the main menu and click Delete Features.

Start editing. Manually select some service locations and secondary lines.

Click the Open Schematic Diagrams button. The Select schematic diagrams to open dialog box appears. Navigate to the Feeders schematic subfolder of the ElecDemo schematic dataset in the C:\arcgis\ArcTutor\Schematics\Schematics\ ElecDemo geodatabase. Click Feeder 0803-Corinth Church in the diagram list and click Add. The diagram appears in a new data frame. Click the Propagate Map Selection To Schematic button. The associated schematic elements in the active diagram are selected. Click the Edit tool and press the Delete key. Save your edits and stop editing.

Click the Schematic menu on the Schematic toolbar and click Update Diagram. Click No if you are prompted whether or not to save the layout.

The Update Diagram dialog box appears and the Initial features option is checked. Click OK.

Right-click the diagram data frame in the table of contents and click Remove.