How can the claims of the Bishop of Rome to the papacy - that is, to not merely be Bishop of Rome or Patriarch of the West, but to be preeminent over all churches wherever - be ended?
Details:
* There needs to actually be a Bishop of Rome who is not making this claim. Simply ending the line of Bishops of Rome (e.g. by a Muslim invasion, or by destroying Christianity) doesn't count.
* Simply moving the Papacy elsewhere while keeping their claims to apostolic succession through Rome (e.g. by an extended Babylonian Captivity) doesn't count either. Having another bishop (e.g. Ravenna) take up those claims on a totally separate basis, however, does count.
* Having there still be someone in Rome making those claims does count, as long as very few people are listening to him. For instance, in OTL, there're now
five different Patriarchs of Jerusalem, including one who pays allegiance to Rome - but no one would say "the Patriarch of Jerusalem acknowledges the Roman primacy."
For easy level, do this with a PoD after the Council of Nicaea. For medium level, do this with a PoD after Charlemagne's coronation. For hard level, do this with a PoD after the Ninety-Five Theses.