You don't need to convert your books to put them on calibre. Just find where they are and add them to your calibre library. It can read epub just fine. ADE doesn't "convert" anyway.
You don't need the acsm files, these were only needed to download the books, and are now probably deleted. You need the epub files. Did you download them through the sony software or ADE? They probably use different folders to store the books. I don't know where sony's is, but a simple search for epub should find it.