It doesn't seem possible that you could convert .edrw files from SolidWorks to anything else, as these are so called eDrawings, CAD files only meant for publishing and viewing not for further editing, similar in purpose as PDF documents.
You will need the original source and export that to STEP format (.step, .stp) instead of making an eDrawing file. The only exception to this is in case the eDrawings were exported in editable fashion, but this would still require SoldiWorks anyway.