You can't take another career branch?
It seems your Sim can only take one career branch. My Sim is in the Chef branch, he quit so he could join the Mixology branch. But the minimum level of the Culinary career he could find is Head Catere...
Forum Discussion
Can't you in the mean time try lowering their career level to before they selected the branch?. I haven't tried the cheat so don't know if possible, but if you can do make a back up of the save files before, JIC
