Start with the sermons people already ask for
A sermon archive becomes useful fastest when it helps with real questions your church already hears. Messages on grief, marriage, prayer, forgiveness, parenting, generosity, suffering, and key Bible passages usually matter long after the original Sunday.
Instead of trying to clean up every old sermon at once, start with the messages your team is most likely to look for again. That creates an early win and helps you decide how to organize the rest of the archive.