Praise be to Allah.
With regard to what you have
mentioned about urinating on an old pickaxe that has been heated with fire
in order to undo witchcraft, this is a myth which it is not befitting for a
monotheist to believe. We have looked at the site which you referred to, and
we saw the one who told you that this action is permissible, but he did not
attribute it to any scholar among the early generation, rather he attributed
it to Ibn al-Qayyim (may Allah have mercy on him). We looked for a place in
which Ibn al-Qayyim stated that it was permissible, and we could not find
it. We do not think that it can be proven to be from him or from any other
early scholar; rather it is more likely to be an action of the charlatans.
And Allah knows best.