If there's a way to do that directly I can't find it either (but that doesn't mean it doesn't exist). You can of course drag the bar back to the bottom, Shift+select all the features, and delete, but I'm sure that's one of those workarounds you're already aware of.
I don't know of a way, but if you are worried about losing your place or accidentally deleting things above where the roll back bar is now, then the way I would do it is the following:
1) Roll back to desired position
2) Roll the freeze bar down to match the position of the roll back bar
3) Roll to end
4) delete everything that isn't frozen (use advanced function in delete window).
There is probably a better way, but this is what I came up with.