How to Hide the "Hydravid" Admin Menu

function plt_hide_hydravid_content_menus() {
	//Hide the "Settings → Hydravid" menu.
	remove_submenu_page('options-general.php', 'hydravid-content/hydravid.php');
}

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

Where do I put this code?