Neal Katyal actually said...

So either he orders the acting attorney general in this case, Rod Rosenstein, to fire Mueller, or somehow just remove -- can he directly rem...

Not exactly. I mean, the rules say, in part 7, they say the following. That the special counsel, 'may be disciplined or removed from office ...

Now, I suspect Rosenstein's answer would be exactly the same, which is, I'm not removing that, heck, no.

It will be hell to pay, it will be the beginning of the end of the Trump presidency if he did it.