How to Hide Five Star Restaurant Reservations - WordPress Booking Plugin Admin Menus

function plt_hide_restaurant_reservations_menus() {
	//Hide "Bookings".
	remove_menu_page('rtb-bookings');
	//Hide "Bookings → Dashboard".
	remove_submenu_page('rtb-bookings', 'rtb-dashboard');
	//Hide "Bookings → Bookings".
	remove_submenu_page('rtb-bookings', 'rtb-bookings');
	//Hide "Bookings → Settings".
	remove_submenu_page('rtb-bookings', 'rtb-settings');
	//Hide "Bookings → About Us".
	remove_submenu_page('rtb-bookings', 'rtb-about-us');
	//Hide "Bookings → Custom Fields".
	remove_submenu_page('rtb-bookings', 'cffrtb-editor');
}

add_action('admin_menu', 'plt_hide_restaurant_reservations_menus', 100);

Where do I put this code?