remove-archive-title-prefix.php

// Removes the 'Project Category:' or 'Category:' part in archive's h1
add_filter( 'get_the_archive_title', function ($title) {
    if ( is_category() ) {
            $title = single_cat_title( '', false );
        } elseif ( is_tag() ) {
            $title = single_tag_title( '', false );
        } elseif ( is_author() ) {
            $title = '<span class="vcard">' . get_the_author() . '</span>' ;
        } elseif ( is_tax() ) {
        	$title = single_term_title( '', false );
        } elseif ( is_archive() ) {
        	$title = post_type_archive_title( '', false );
        }
    return $title;
});