@oliver: If you are trying to hide it then you can just add css in “Appearance => Theme Options => Custom CSS” box and hide it. But if you want to edit the functions then you need to buil child theme and create the file functions.php and then add the following Code and edit as per your wish.
function catcheverest_header_meta() {
$date = sprintf( '<a href="%1$s" title="%2$s" rel="bookmark"><time class="entry-date" datetime="%3$s">%4$s</time></a>',
esc_url( get_permalink() ),
esc_attr( get_the_time() ),
esc_attr( get_the_date( 'c' ) ),
esc_html( get_the_date() )
);
$author = sprintf( '<span class="author vcard"><a class="url fn n" href="%1$s" title="%2$s" rel="author">%3$s</a></span>',
esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
esc_attr( sprintf( __( 'View all posts by %s', 'catcheverest' ), get_the_author() ) ),
get_the_author()
);
// Translators: 1 is category, 2 is tag, 3 is the date and 4 is the author's name.
$utility_text = __( '<span class="on-date">Posted on %1$s</span><span class="by-author"> by %2$s</span>', 'catcheverest' );
printf(
$utility_text,
$date,
$author
);
}
