If you're referring to generator-style async/await, you can change that now.
Otherwise you can just prettify it and be on your way.
Sure you don't want to go back, but that's the whole reason TS exists: writing JS with good organization and discipline is impossible at worst, full of boilerplate at best.
You do not want to work on that. It readable to an extent, but it's definitely not pleasant.
I don't think you could just go back.