That would require an act of congress, which, while not impossible, is very unlikely given the current situation. some congressional republicans are pissed at him right now, and they have an extremely slim majority, so any defections on such a vote would prevent it from passing.

Maybe?

It's relatively easy to tell an American company not to provide a product, like they did with Google/Apple and TikTok.

De-listing a website on a national level is considerably more difficult, especially without something equivalent to China's Firewall.

It's why Pirate Bay still exists.