It seems that the demolition, on 10 January, took place, in error: Sheffield City Council told Now Then magazine: “Our initial belief was that the top turret on the building had collapsed under its own weight on the morning of 10 January.”
“New information has since come to light which shows the demolition company were instructed in error at 11:53am to continue with demolition. As a result of this order, our understanding is the turrets fell because of the recommenced demolition works.”