abandon CLASS
This command will allow a player to abandon a class completely or allow them to abandon enough levels in the class to drop them back down to the nearest multiclass level block. A player must be level 11 or higher in order to be able to use this command. It will drop a level 11-20 player down to level 10, a 21-30 player to level 20, and a 31-40 level player to level 30.
All of your feats and skills will be reset when you abandon a class, but you will be allowed to pick an amount of free feats that are equal to the amount of feats you previously had. You can't spend more free feats than you are allowed at your current level, but they will remain until you have gained enough levels to use them later, even if you abandon more levels or classes before that time.
All of your stats will be preserved. You need to use stats command to move them around.