In Free subscription, you can’t. We are proud to empower anyone to create compelling, high quality, and fun simpleshow videos for free. Accepting our branding logo is the only thing we ask for in return 🙂
In Business subscription you can hide the mysimpleshow watermark in Finalize stage.
You are able to upload your own watermark in Pro subscription. Take a look at this article: How do I use the Finalize stage?