Can a Pope be impeached?
But I think it was more of an inside coup than an impeachment.
I've read that such a thing would only be possible if the original papal election was somehow invalid. For example, if it could be shown that Francis was not in fact a Catholic at the time of his election, he would be ineligible to become Pope, and his election would be invalid.
It would be interesting to hear from some Freeper who really knows Church law.
Perhaps the pope can breed with him