How do you ban bitcoin? It’s not hosted or supported by American financial rails or any entity like swift which can be influenced by the USA in any meaningful way.
You could make it prohibitively problematic to use for most things.
You do what the the US is doing right now to starve Cuba & end civilization there: you embargo/sanction anyone doing business there.
Like the Treasury/Dept of Commerce & others did with North Korean backed Tornado Cash. Some very quickly retrieved/not well researched (caveat reader) search links; https://home.treasury.gov/news/press-releases/jy0916 https://www.paulhastings.com/insights/crypto-policy-tracker/...
It's supported and influenced by the USA in the sense that if you can't ever turn it into dollars it becomes much less interesting.