How to Hide Bulk Datetime Change Admin Menus

function plt_hide_bulk_datetime_change_menus() {
	//Hide the "Bulk Datetime Change" menu.
	remove_menu_page('bulkdatetimechange');
	//Hide the "Bulk Datetime Change → Bulk Datetime Change" menu.
	remove_submenu_page('bulkdatetimechange', 'bulkdatetimechange');
	//Hide the "Bulk Datetime Change → Settings" menu.
	remove_submenu_page('bulkdatetimechange', 'bulkdatetimechange-settings');
}

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

Where do I put this code?