The Turn Centerlines Off command turns conduit and cable tray centerline layers off. These layers are typically on a non-plotting layer that will not appear on your printed drawings. It is often helpful during the design to turn these centerlines on and off to see what your final drawing will look like.
To turn the centerlines off, go to
Ribbon: DM Electrical->3D-BIM-> 
Turn Centerlines Off
Pulldown Menu: DM Electrical->Layer Management->Turn Centerlines Off
The centerline layers will be turned off and will not be visible on the drawing.