Why didn't we just "unplug" Hitler and Goebbels? Or Marshall Applewhite? You don't need a powerful physical body(s) to cause tremendous amounts of harm before anyone can stop you. To most people of the time Hitler was a persuasive powerful voice on the radio, or words in a paper - things SOTA generative AI are already phenomenal at.
A super-smart AI may be intensely popular with many people in the way that some politicians are. It may understand us and speak to us on a seemingly-personal level, the way the best politicians do. A lot of us could support the super-smart AI for that reason.
Hitler could have been assassinated. It was tried multiple times:
https://en.wikipedia.org/wiki/List_of_assassination_attempts...
None of these attempts failed because the act of assassinating Hitler was technically impossible, they failed to chance, unfavorable conditions, intervention, human error, etc. Given enough attempts, eventuelly one of them would have succeeded.
"We tried to shut down the AI multiple times. It killed many millions of people but eventually we did it! You see, AI is safe!"