add_filter( 'aioseo_breadcrumbs_trail', 'aioseo_breadcrumbs_trail' );

function aioseo_breadcrumbs_trail( $crumbs ) {

	foreach ( $crumbs as $key => $crumb ) {

		if ( is_a( $crumb['reference'], 'WP_Term' ) && 'uncategorized' === $crumb['reference']->slug ) {

			unset( $crumbs[ $key ] );

		}

	}

	return $crumbs;

}