How to Hide StellarPay - Stripe Payment Gateway for WooCommerce Admin Menus

function plt_hide_stellarpay_menus() {
	//Hide the "StellarPay" menu.
	remove_menu_page('stellarpay');
	//Hide the "Tools → Scheduled Actions" menu.
	remove_submenu_page('tools.php', 'action-scheduler');
}

add_action('admin_menu', 'plt_hide_stellarpay_menus', 11);

Where do I put this code?