As it is, the Pope does not unilaterally fire bishops. As far as I know (and I am no canonical expert) ordinarily bishops' offices can only be vacated by death, resignation, or specific violation of canon law, of which the bishop has been convicted in a canonical court.
Now in my opinion, almost each and every Bishop in the USA is in violation of Canon 915, to which I alluded before.
Archbishop Raymond Burke, the head of the Church equivalent of the "Supreme Court" in Rome, is apparently in agreement that these bishops are violating canon law, but it has all become a huge controversy in the church, partly because of the Church's desire to leave civil government in the hands of civil government, and not be seen as trying to control governments through means of church discipline.
The outcome of this is far from certain.
I have very strong views on it myself, but of course, I'm not the pope. (By the way, I just talked about this and related topics, to a member of my bishop's staff yesterday.)
Please pray for us. We urgently need it.
We pray for all Christians in the world. The spiritually pure leaders of all Christian faiths need to speak out forcefully and take action. The Lord Jesus demands it.