Try the chain anchor point

The chain is anchored to a big ring atop a massive screw, screwed directly into the floor. In theory, you should be able to unscrew it.

If you were as strong as a rhino.

There's nothing within your reach that you can use as leverage, so your only option is to struggle with the screw with your bare hands, forcing your weight against it. After a few minutes it hasn't moved at all, and you have to give up, exhausted.