How to Hide Smitacs Pos Invoice Admin Menus

function plt_hide_smitacs_pos_invoice_menus() {
	//Hide "POS INV".
	remove_menu_page('smitacs-pos-invoice');
	//Hide "POS INV → POS INV".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice');
	//Hide "POS INV → Settings".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-settings');
	//Hide "POS INV → Pembukuan Usaha".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-pembukuan-sederhana');
	//Hide "POS INV → Kasir".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-mypos');
	//Hide "POS INV → Invoice".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-invoice');
	//Hide "POS INV → Saldo".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-saldo');
	//Hide "POS INV → Payment".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-payment');
	//Hide "POS INV → Produk".
	remove_submenu_page('smitacs-pos-invoice', 'smitacs-pos-invoice-produk');
}

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

Where do I put this code?