The Erase Conduit Run command is used to erase a conduit and all of the pieces of conduit connected to it. Use this command when you need to easily erase a whole run of conduit from the drawing.
To erase a run of conduit, go to
Ribbon: DM Electrical->3D-BIM-> 
Erase Conduit Run
Pulldown Menu: DM Electrical->Conduits->Erase Conduit Run
You will be prompted to identify which conduit run is to be erased.
Select conduit run to erase:
The selected conduit and all of the conduits connected to it will be erased.