In fact, for an epub, nothing calibre specific in the metadata is needed or required. Just the same way that nothing Sigil specific in the metadata is required. Things like the MOBI-ASIN are for personal use only as they are not needed or required for an epub.
In fact, other than the main dc:identifier, the dc:title, and dc:language, nothing else is required by the epub spec. Of course, adding at least one author is strongly recommended!
Everything else is there just for the user's info and can be deleted if you want. That said, if you use calibre to manage your ebook library and are not creating an epub for others to use, you can just as easily leave it there. It won't hurt anything.
btw: none of the old meta style is allowed to be used in epub3, so none of the calibre: prefixed name/content pairs will be read or used by any epub3 software and may be deleted depending on the software/tool.
KevinH