How to Hide Smitacs PPOB Gateway Admin Menus

function plt_hide_smitacs_ppob_gateway_menus() {
	//Hide "PPOB Distributor".
	remove_menu_page('smitacs-ppob-gateway');
	//Hide "PPOB Distributor → PPOB Distributor".
	remove_submenu_page('smitacs-ppob-gateway', 'smitacs-ppob-gateway');
	//Hide "PPOB Distributor → Settings".
	remove_submenu_page('smitacs-ppob-gateway', 'smitacs-ppob-gateway-settings');
	//Hide "PPOB Distributor → Saldo".
	remove_submenu_page('smitacs-ppob-gateway', 'smitacs-ppob-gateway-saldo');
	//Hide "PPOB Distributor → Payment".
	remove_submenu_page('smitacs-ppob-gateway', 'smitacs-ppob-gateway-payment');
	//Hide "PPOB Distributor → Produk".
	remove_submenu_page('smitacs-ppob-gateway', 'smitacs-ppob-gateway-produk');
}

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

Where do I put this code?