Sims 3 Launcher won't let me uninstall custom content

I'm having the same problem. I was playing and then when I aged up my sim they had a female YA/A shirt and they were only a toddler, so I found out that it was one of my downloaded sims from TSR and I tried uninstalling her but first it said that it failed to uninstall her then I took her out of my "SavedSims" file and then I tried again and it popped up saying :Error😛ackage could not be found. Just like you I'm very confused and I'm not good on working with the sims stuff.