How to convert a part from higher version to a lower version??

With Pro/E you cannot open a model that was created with a higher version and there is no down save option. The only way is to export as stp or iges and open it in a lower version.

Only with playing with formats,export as STEP then open in your proe vers.

What should you do?

Can not be
only through the side of formats.

Ніяк не можна
можна тільки через стороні формати.

i think you must save the file with higher CAD software to low version and you can open the file with the low version CAD software.

hope to help