Gold foil and gold dust can destroy Mondas Cybermen, or at least disable them for a while. Gold dust blocked their respiratory systems. The Paralell Earth Cybermen have no weakness to gold. Instead of gold, their weakness lies in their emotional inhibitors, which makes them think like a Cybermen. If these are disabled, they will realise what they have become, go mad and self-destruct.
Other than that, both generations of Cybermen can be destroyed by Dalek gunfire and severe electrocution.