Need help!

https://preview.redd.it/36oq1p75dzsd1.png?width=1558&format=png&auto=webp&s=aa33d74cf37a8b8c75291c526a5974ae22cfebd5

Hii! I'm a student in modeling and still in the learning process. I am trying to Unwrap this, but it stays all selected and create like triangle? How do I turn that off to have the "normal" Unwrapping selection?
Thanks!