also, if in your house(via a home sweet home) you can talk to the housekeeper to change classes, or there is a npc in varanas class hall that will let you switch as well.
I recommend changing gear to the new class before switching to save on healing. This can be done with gear in the different gear loadouts in character screen. Or switch, change gear, switch, the switch back. It becomes a little bit more useful at higher levels with more gear.