How to remove unwanted skills

Hi everyone! I've recently started playing TS4 after a hiatus of several months. I got the new Life and Death pack and some recent kits. One thing I've noticed is that now I can no longer bring a skill to 0 using the cheats. In the past I used to do that to get rid of skills my Sims had started to learn but that didn't really fit the character I had in mind. 

For some reason this cheat is no longer working. I don't know if it has anything to do with the new pack/kits I've recently purchased. 

I play vanilla (no mods) on a Mac. 

Any ideas? Is anybody experiencing the same problem? Is there a new way to remove unwanted skills?

Thanks!