InDesign lets you specify an external css file to use for the epub. You just need to make sure that the selectors in this file match the names of the styles that you've used in your InDesign document and that's what will appear in the epub.
If you're using this feature then you have to specify all
the styling in the external css file, as InDesign won't generate any styles itself. So you can create a css file like
then create paragraph or character styles in InDesign named 'normal', 'flush', 'head1' and 'hidden'. Any text which has been given the style named 'hidden' will not appear in the epub, though it will still be present in the xhtml code.