How to Hide the "Sentry" Admin Menu

function plt_hide_wp_sentry_integration_menus() {
	//Hide the "Tools → Sentry" menu.
	remove_submenu_page('tools.php', 'wp-sentry');
}

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

Where do I put this code?