How do I hide ‘out of stock’ products in the admin ‘product’ page?

You can do that by adding the code below on your theme functions php file.

add_action( 'pre_get_posts', 'iconic_hide_out_of_stock_products' );

function iconic_hide_out_of_stock_products( $q ) {

if ( ! $q->is_main_query() || is_admin() ) {
    return;
}

if ( $outofstock_term = get_term_by( 'name', 'outofstock', 'product_visibility' ) ) {

    $tax_query = (array) $q->get('tax_query');

    $tax_query[] = array(
        'taxonomy' => 'product_visibility',
        'field' => 'term_taxonomy_id',
        'terms' => array( $outofstock_term->term_taxonomy_id ),
        'operator' => 'NOT IN'
    );

    $q->set( 'tax_query', $tax_query );

}

remove_action( 'pre_get_posts', 'iconic_hide_out_of_stock_products' );

}

This code was tested on the font end but it can easily be adapted to the back end

More info can be found here on this link https://iconicwp.com/hide-stock-products-woocommerce-catalog-pages/