I am looking for two movie titles.

They are horror movies from the 80's

1. College students stay in a dept store over night and they start to get murdered. I remember some girl head gets cut off by an elevator.

2. Female college students are being killed at school. It ends up being a college profersor. They die from shocking and plaster.

If you know the movie titles, please post.

Thanks

First one might be Chopping Mall with the killer robots in a mall killing nubile youngsters.

Not what I expected when I read the thread title quickly

The first one might be Dangerous Game (1987), an Aussie thriller with a plot just as you describe it. I don't recall a decapitation scene. The Initiation (1984), which also takes place in a mall, supposedly has a decapitation scene, though I don't recall it.
Second one might be Fatal Pulse (1988)

I like some big ol' movie tittles too.

I believe the first one is Hide and Go Shriek...

http://www.imdb.com/title/tt0095299/



Pretty creepy film



No sure about the 2nd one, maybe Night School

1st sounds like The Initiation.