Don't understand totally of what you mean. If you want to get the original polyShape back from the converted subD, you can make a deplicate of the subD, then run a convert subD to poly and delete the tessShape.
You said nothing about not wanting the history, so I assume you need it. If you don't want that, just use "vertices" for the tessellation method and level "0" when convert the subD to poly. Then instead of deleting the tessShape, delete the "HistPoly".