That would be news to all the other Christian churches who declared someone a saint without the Pope's permission, as well as all the first millennia Catholics who did so as well.
So show me the proof where God himself declared this person or that a Saint. We can show definitive proof that men/women have honored people as Saints. While other sects of Christianity may indeed proclaim someone a Saint, the preponderance of Saints, through out history, have been so proclaimed within the Catholic Church. Nor is it even limited to just Christianity, as the Jewish religion did the same, but were usually not referred to as Saints.
Thus I was speaking more in general terms rather than speaking in literal terms when I said the Pope. I did so because he is the most recognizable head of a church structure, and Sainthood is associated by most everyone as a Catholic designation.
If you can provide undeniable proof that everyone who who has been proclaimed a Saint, did so with direct communication through God, then I will acquiesce. Until then it is a function controlled entirely by mankind within the hierarchy of the church structure.