I can't figure out the name of a movie. Its about a little girl who tries to kill her family. She throws a radio in the tub with her mom or dad. She walks around the house with a pizza cutter at some point in the movie.. That's all that I can remember.

It's called "Don't Go to Sleep"

It has Dennis Waever in it as the father. It's kind of a twisted ending, so I won't reveal it here.

I can't figure out the name of a movie. Its about a little girl who tries to kill her family. She throws a radio in the tub with her mom or dad. She walks around the house with a pizza cutter at some point in the movie.. That's all that I can remember.
That's the movie don't go to sleep

Don't Go to Sleep (1982) (TV) (http://imdb.com/title/tt0083844/)

YouTube - Don't Go to Sleep - Dad & Pizza Cutter Scene (http://youtube.com/watch?v=3xtnh2a5xug)
( that's the pizza cutter scene)

Watch the rest from that user
:)
Enjoy