It was pre-cut. It annoyed the hell out of me when I picked up the first DVD release and found it cut, as that bit when he shoots pop's is great.
However, the UK Collector's Edition from Sanctuary is UNCUT. It's a nice package with an audio commentary etc. By the way, when Channel 5 showed this, they kept the shooting of Dad but cut the bit when the little sister puts a plastic bag over her brothers head! Twits.
Here is a link to the uncut UK release:
Amityville 2 Uncut UK (Amazon)