Is it possible to switch factions in Planetside 2 after choosing one?
You can create a new character for the other faction, however you will lose all your unlocks. They currently have no way to switch you to another faction and maintain your unlocks.
You have two options: you can delete your existing character (and all his unlocks) and create him again on the same server as a different faction, or, you can keep him, and create a new character on a different server as a different faction, starting at 0 certs again. Keep in mind you only get 3 character slots, though you may be able to buy additional character slots with station cash.