Ok now at pc, and after playing my melee chap, It seems there is no way to turn it off competently, the clickable option "Elaborate executions" only turns off the slow motion camera, not the executions themselves.      

Game options, on the left with the list to turn off the torch, change the circle under you etc, Im not at my pc so cant give a better description,but its a clickable option, and above the otptions for the normal/tac stuff.