Tips on Customizing Car Dealer (Dealership) and Vehicle sales

How to Hide CarDealer Admin Menus

function plt_hide_cardealer_menus() {
	//Hide "Appearance → CarDealer Designer".
	remove_submenu_page('themes.php', 'Car_Dealer_Designer');
	//Hide "Installing New Plugin".
	remove_menu_page('bill_pre-checkup');

	//Hide "Car Dealer".
	remove_menu_page('car_dealer_plugin');
	//Hide "Car Dealer → Dashboard".
	remove_submenu_page('car_dealer_plugin', 'car_dealer_plugin');
	//Hide "Car Dealer → Settings".
	remove_submenu_page('car_dealer_plugin', 'cardealer-settings');
	//Hide "Car Dealer → Fields Table".
	remove_submenu_page('car_dealer_plugin', 'fields-table');
	//Hide "Car Dealer → Cars Table".
	remove_submenu_page('car_dealer_plugin', 'cars-table');
	//Hide "Car Dealer → Makes".
	remove_submenu_page('car_dealer_plugin', 'md-makes');
	//Hide "Car Dealer → Locations".
	remove_submenu_page('car_dealer_plugin', 'md-locations');
	//Hide "Car Dealer → Team".
	remove_submenu_page('car_dealer_plugin', 'md-team');
	//Hide "Car Dealer → CarDealer Designer".
	remove_submenu_page('car_dealer_plugin', 'md-designer');
}

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

Where do I put this code?

How to Hide the "Details" Meta Box

function plt_hide_cardealer_metaboxes() {
	$screen = get_current_screen();
	if ( !$screen ) {
		return;
	}

	//Hide the "Details" meta box.
	remove_meta_box('listing-details', $screen->id, 'normal');
}

add_action('add_meta_boxes', 'plt_hide_cardealer_metaboxes', 20);