How to Hide the "Easy Image Optimizer" Admin Menu

function plt_hide_easy_image_optimizer_menus() {
	//Hide the "Settings → Easy Image Optimizer" menu.
	remove_submenu_page('options-general.php', 'easy-image-optimizer-options');
}

add_action('admin_menu', 'plt_hide_easy_image_optimizer_menus', 61);

Where do I put this code?