To my knowledge situation outfits cannot be edited at all. And the only way to disable them is with mods- yet I'm not sure whether using a mod to disable them will solve your problem. Also, since all of the situation outfits use that same slot, you'd have to guess which mod you have to install in order to disable that particular situation outfit (or install all of the available ones)
MCCC has a few options to get rid of some of them. There was also a (german?) website somewhere that had a lot of mods to remove most of them but I don't remember the name.
I think by the time I got done doing all that, I'd rather just copy and paste the sim's appearance onto a fresh one with MCCC and hope that works instead.
