The only safe, reliable way to achieve a export is to purchase a license. Once you buy a plan, the watermark disappears instantly from all future exports.
If you have already exported a video with a watermark and no longer have the original project file, there are limited ways to clean it up: AI Object Remover (Filmora 13 Feature) : You can use the built-in AI Object Remover wondershare filmora 13 no watermark