When changing to the vanilla mode, the starting point and the energy interface are not removed.

That's expected and intended.
All items, apart from secondary and primary electric interfaces, exist in base game.

However, you can produce items you could not produce in the past.

You can save the mode file, remove the mode, and load it from vanilla to create a starting point and energy interface.

:o

You can also load any save into map editor, place the items from there and continue playing.
This mod just saves converting saves to scenarios.