When you select a frame, the links appear for that frame, and all frames within it, but you can only easily “-” remove the frames on the top level one, as far as I can tell?
Often when prototyping I am duplicating lots of top parent frames, and sometimes the persistent underlying prototyping interactions are helpful but eventually you get a to a point where you have too many…and it is just annoying to remove them one by one.
I can just delete my response here – but it’s possible it might be helpful for others who end up visiting this post: flows-missing-from-preview-sidebar/