Answer:
It is likely that they'd have used siege weapons of the same types used during warfare. One of these may have been the onager, though this is questionable as it might not yet have been invented by the time of the Second Temple's destruction in 70 CE (AD). They would almost certainly have used battering rams, in those times of the most effective methods of demolition. Another common method of bringing down walls was to dig hollows shored up by wooden posts, similar to those used in mines, under weak spots such as corners. The posts would then be burned, causing the wall to lose its support and collapse.