eDrawing files (.easm) typically cannot be converted to anything else, because they are used as previews and for printing - not for further editing, which makes any easm conversion troublesome - including export to IGES format format.
If you need STEP CAD data from a Solidworks drawing, you need to have the original exported as IGES (.igs, .iges). Some versions of eDrawing also allow the author to "unlock" the files for further use.