xarxaprod-wp-theme/inc/archive-title.php

<?php
/**
 * Archive title customization.
 * Get rid of the "Category:" "Tag:" "Author:" "Archives:" lables in 
 *
 * https://developer.wordpress.org/reference/functions/get_the_archive_title/#comment-1807
 */


function xarxaprod_archive_title( $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_post_type_archive() ) {
		$title = post_type_archive_title( '', false );
	} elseif ( is_tax() ) {
		$title = single_term_title( '', false );
	}

	return $title;
}

add_filter( 'get_the_archive_title', 'xarxaprod_archive_title' );