Display only sub-categories in Taxonomy Badge

child-categories.txt

Add the following filter in your active child theme's functions.php file

add_filter( 'uael_posts_tax_filter', function( $terms ) {
	$child_terms = array();
	$terms = wp_get_post_terms( get_the_ID(), 'category' );

	foreach( $terms as $term ){
		if( $term->parent !== 0 ){

			array_push( $child_terms, $term );
		}
	}

	return $child_terms;	
}, 10, 2 );