Can you use the Armory Station to load a saved build from before you subclassed-- or, if you've never saved a build, to reset your character? I haven't tried subclassing yet, so I'm not sure how it all works. Edit: Warning-- When I say "reset your character," I do mean reset it. You may wish to take screenshots of your attributes, skills, CPs, etc., before you reset everything.
Talk to the subclassing NPC again. $1500
Use a Rededication Shrine, the one that deals with skill points. Those now have subclassing on the menu. $1500
Use a scroll as mentioned above by @M_Volsung
Fan of playing magblade since 2015. (PC NA) Might be joking in comments.
-->(((Cyrodiil)))<--