Repeat after me: nobody can judge of a pope.
That means that nobody is invested with the authority level official judgments against a pope. It's not possible to drag someone recognised as the Pope before the Inquisition or to have a body of bishops judge him. He can be corrected, but he cannot be judged.
Pope St. Nicholas, epistle (8), Proposueramus quidem, 865: “… Neither by Augustus, nor by all the clergy, nor by religious, not by the people will the judge be judged… ‘The first seat will not be judged by anyone.’"
Pope St. Leo IX, In terra pax hominibus, Sept. 2, 1053, Chap. 32: “… As the hinge while remaining immoveable opens and closes the door, so Peter and his successors have free judgment over all the Church, since no one should remove their status because ‘the highest See is judged by no one.’”
Canon 1556, 1917 Code of Canon Law, On trials in general: “The First See is judged by no one.”
No ONE PERSON can judge a Pope, that's true. And there isn't a set doctrine in regards to how to deal with a heretical Pope. Surely you know that. Various theologians have different formulas for dealing with the possibility for a Pope who is in heresy.
Sedevacantists tend to believe that the Pope is equal to God, but he isn't. He can be judged by a body of men. How it is that they separate a heretic Pope from the papacy is not clear.
You can quote canon law till the cows come home in defense of your position, but quotes can be provided to the contrary.
We do not live in the wild west, where law doesn't matter, and where the populace then takes matters into their own hands and administers frontier justice. That's not how the Church works.