I've had this app (SIM Toolkit) since forever and can't seem to find a way to remove it.
SIM Toolkit brings up a list of things like horoscopes, music videos, chat etc. It depends on your service provider and you're not really missing much by not being able to use it! You can't delete the app if your phone isn't rooted.
You can remove it if you're S-OFF/using a custom ROM. Just remove stk.apk from
But in my opinion leave it, don't bother removing it because it's really small app.