If the platys start showing stress or any fin or body damage, I would remove her. But once she has established her territory, she might calm down--that usually does take a few days. I don't have first hand experience in this though, so I might be mistaken.
So, in your more educated opinion, is this a boy in the picture? I wondered...A 10 gallon is too small to have a proper betta fish community tank. I would remove the betta and place him in his own tank. Or you could upgrade the tank to a 20 gallon.
Betta fish are extremely territorial and a 10 gallon doesn’t offer him enough space to feel comfortable owning an area of the aquarium (with the presence of other fish). He’s competing with the other fish for territory.
I’m not really sure, honestly. It’s probably female.