It is impossible to re-define after your 6th time as you cannot carry enough gold
I’ve made a mistake can I go back? Yes you can, but if you do you will not gain the class promotion once again, this WOW PowerLeveling is to prevent abuse.
This can be done at your race Hero, going to see this NPC allows you to “Re-define” your class; this costs Gold with the cost increasing each time it takes place. Originally costing 1000Gold pieces, it then adds a 0 each time.
Re-definition will not cause your character to be "gimped" in anyway after doing so, no matter what class you have re-defined from, it gives you a clean slate resetting your character to the original class you were.
It is then impossible to re-define after your 6th time as you cannot carry enough gold in your inventory to do so. What this means:
If a Warrior Cross Classed into a Ranger they could max out their Melee PT, Range PT and Force PT.
If a Ranger Cross Classed into a Warrior they could max out their Range PT, Melee PT and Force PT.
If a Spiritualist Cross Classed into a Warrior they could max out their Melee PT and Force PT but not their Range PT.
If a Specialist Cross Classed into a Warrior they could max out their Melee PT and Force PT but not their Range PT.