To delete a wire from your model, whether catenary or auxiliary, just follow these steps.
Please note: Deleting a wire will also delete all equipment that is attached to the wire.
Step 1: Open 'Wire Manager' from the 'Wires' section of the Lineardraft toolbar
Step 2: Select the wire you want to delete from the 'Selected Wire' dropdown
Step 3: Click the 'Delete' button
See also: Detaching a Wire from a Structure