Once you have done the orc fort quest outside Kingsbridge. Go to New Garand, there is a tower next to the weapon merchant. That's the warriors guild, go in talk to the bouncer, he will let you in(before you have completed the above quest he won't) once you get into the guild area go right and talk to the NPC.
Be aware that costs esculate dramatically so carefully plan what it is you want to change ! (Currently I use this for getting rid of skills and traits points spends on companions that are not optimised for how I wish them to act.....)