How to Hide S2 Donation using Stripe Admin Menus

function plt_hide_s2_donation_using_stripe_menus() {
	//Hide the "S2 Plugins" menu.
	remove_menu_page('s2-admin');
	//Hide the "S2 Plugins → Donation" menu.
	remove_submenu_page('s2-admin', 's2-donation');
}

add_action('admin_menu', 'plt_hide_s2_donation_using_stripe_menus', 11);

Where do I put this code?