ORD - Remove feature definition from line

aa.dgn

Is there a way to remove feature definition from lines or arcs?  I have added feature definition to normal Microstation lines to used them in corridor but now I would like to remove the feature definition from them.  Or at least drop them but every time I drop them they disapear from the drawing.  Is this a normal behavior?

Also is there a way to just drop civil offset line to normal microstation line without feature definition?