On my Roku, model SE, there isn't a Settings/Accessibility menu.
While watching an ABC show, I pressed the * key as others have suggested. That brings up Closed Captions <off>, press down to Audio Language <blank>, press left and it's still <blank>, but the descriptive audio is gone. I think the options are there, just not visible.
I finally stopped it on the ABC App. I changed the language from *English to English #2. There was three options and the 2nd "English" fixed it. Now, it only shows "default" as a choice and I can't change it