How to Hide SmartPay Admin Menus

function plt_hide_smartpay_menus() {
	//Hide "SmartPay".
	remove_menu_page('smartpay');
	//Hide "SmartPay → Dashboard".
	remove_submenu_page('smartpay', 'smartpay');
	//Hide "SmartPay → Products".
	remove_submenu_page('smartpay', 'smartpay#/products');
	//Hide "SmartPay → Forms".
	remove_submenu_page('smartpay', 'smartpay-form');
	//Hide "SmartPay → Customers".
	remove_submenu_page('smartpay', 'smartpay#/customers');
	//Hide "SmartPay → Coupons".
	remove_submenu_page('smartpay', 'smartpay#/coupons');
	//Hide "SmartPay → Payments".
	remove_submenu_page('smartpay', 'smartpay#/payments');
	//Hide "SmartPay → Settings".
	remove_submenu_page('smartpay', 'smartpay-setting');
	//Hide "SmartPay → Integrations".
	remove_submenu_page('smartpay', 'smartpay-integrations');
	//Hide "SmartPay → ⭐ Upgrade to pro".
	remove_submenu_page('smartpay', 'https://wpsmartpay.com');
	//Hide "SmartPay → Getting Started".
	remove_submenu_page('smartpay', 'wpsmartpay-getting-started');
}

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

Where do I put this code?