Hide Out-of-Stock Products From Catalog

<?php
if ( ! class_exists( 'WooCommerce' ) ) {
    return;
}

add_action( 'woocommerce_product_query', 'scseed_hide_outofstock_products' );
function scseed_hide_outofstock_products( $q ) {
    $meta_query = (array) $q->get( 'meta_query' );
    $meta_query['scseed_stock_filter'] = array(
        'key'     => '_stock_status',
        'value'   => 'instock',
        'compare' => '=',
    );
    $q->set( 'meta_query', $meta_query );
}