The US Blu-ray release from Shout! Factory has the scene with man's head being ripped off intact.
Both the 1986 UK VHS version & the current US DVD version are missing a small scene during the carnival massacre where a man has his head torn off. This was intact in the original UK cinema print.
The Japanese DVD under the title "Monster (Humanoids From The Deep)" is the full uncut version including the shot of a man having his head ripped off. It is presented in 1.85:1 widescreen (no anamorphic enhancement though) and looks much better than the slightly cut region 1 DVD.