How to Hide the "S3 Smart Upload" Admin Menu

function plt_hide_wp_s3_smart_upload_menus() {
	//Hide the "Media → S3 Smart Upload" menu.
	remove_submenu_page('upload.php', 's3-smart-upload-settings');
}

add_action('admin_menu', 'plt_hide_wp_s3_smart_upload_menus', 11);

Where do I put this code?