How do you send your followers to their original homes after sending them to a settlement?
If you're not averse to mods, one that's just been uploaded to the Nexus yesterday lets you do exactly that - send your companions back to their original homes. It's here:
Companions Go Home - http://www.nexusmods.com/fallout4/mods/10029/
NPCs do not remember their initial hometown once they are send to a settlement. Because of that, there is no way of sending them back without the usage of console commands.