ST ROBERT BELLARMINE (Refuting the eight conditions proposed by the Lutherans for celebrating a Council):
The third condition is unjust, because the Roman Pontiff cannot be deprived of his right to summon Councils and preside over them... unless he were first convicted by the legitimate judgement of a Council and is not the Supreme Pontiff. Moreover... the supreme prince, as long as he is not declared or judged to have legitimately been deprived of his rule, is always the supreme judge, even if he litigates with himself as a party.
The sixth condition is unjust and impertinent. Unjust, because inferiors ought not be free from the obedience to superiors, unless first he were legitimately deposed or declared not to be a superior... Furthermore, it is impertinent because that oath does not take away the freedom of the bishops, which is necessary in Councils, for they swear they will be obedient to the supreme Pontiff, which is understood as long as he is Pope, and provided he commands these things which, according to God and the sacred canons he can command; but they do not swear that they are not going to say what they think in the Council, or that they are not going to depose him if they were to clearly prove that he is a heretic.
ST ROBERT BELLARMINE (Answering doubts on Councils):
The second, whether or not it is lawful for a Council to be summoned by anyone other than the Pope when the Pope should not summon it, for the reason that he is a heretic or schismatic... To the second and third, I respond... in those two cases an imperfect Council could be gathered which would suffice to provide for the Church from the head. For the Church, without a doubt, has the authority to provide for itself from the head... Hence, that imperfect Council can happen, if either it is summoned by the college of Cardinals, or the bishops themselves come together in a place of themselves.
ST ROBERT BELLARMINE (On secret infidels):
Moreover, it is certain, whatever one or another might think, a secret heretic (my insertion - one who is guilty of the SIN of heresy), if he might be a bishop or even the Supreme Pontiff, does not lose jurisdiction, nor dignity, or the name of the head in the Church, until either he separates himself publicly from the Church, or being convicted of heresy is separated against his will.
ST ROBERT BELLARMINE (On secret infidels):
Two things can be considered on Bishops: Firstly, that they hold the place of Christ so for that reason we owe obedience to them... Secondly, that they might have the power of Order and Jurisdiction. If it is considered in the first mode, we are certain with an infallible certitude that these, whom we see, are our true Bishops and Pastors. For this, neither faith, nor the character of order, nor even legitimate election is required, but only that they be held for such by the Church... Now if this is considered in the second manner, we do not have any but a moral certitude that these will truly be Bishops, although it is certain with infallible certitude that at least some are true, otherwise God will have deserted the Church...
ST ROBERT BELLARMINE (On the Marks of the Church - Apostolic Succession):
...we cannot depose catholic bishops who have possessed their sees for so many canturies peacefully, unless they are legitimately judged and condemned; for in every controversy, the condition of the one possessing it is better...
ST ROBERT BELLARMINE (On deposition of bishops):
...if the pastor is a bishop, they (the faithful) cannot depose him and put another in his place. For Our Lord and the Apostles only lay down that false prophets are not to be listened to by the people, and not that they depose them. And it is certain that the practice of the Church has always been that heretical bishops be deposed by bishop's councils, or by the Sovereign Pontiff...
Add to these quotes those previously furnished by Sean that indicate clearly that St Robert requires monitions to demonstrate pertinacity (formal heresy) of the heretic Pope and some kind of judgement/declaration of the public facts by the Church.
This is getting tiresome:
St. Robert Bellarmine:
“A Pope who is a manifest heretic automatically ceases to be a Pope and head, just as he ceases automatically to be a Christian and a member of the Church. Wherefore, he can be judged and punished by the Church. This is the teaching of all the ancient Fathers who teach that manifest heretics immediately lose all jurisdiction.”
St. Alphonsus Liguori:
“If ever a Pope, as a private person, should fall into heresy, he should at once fall from the Pontificate. If, however, God were to permit a pope to become a notorious and contumacious heretic, he would by such fact cease to be pope, and the apostolic chair would be vacant.”
St. Francis de Sales:
“Now when the Pope is explicitly a heretic, he falls ipso facto from his dignity and out of the Church . . . ”
St. Antoninus:
“In the case in which the Pope would become a heretic, he would find himself, by that very fact alone and without any other sentence, separated from the Church. A head separated from a body cannot, as long as it remains separated, be head of the same body from which it was cut off.”