How can I treat a worm like parasite on the sole of my foot. It is very itchy I have been using cortisone cream but it is not working The worm is visible through the skin I can see it as it moves?

You should seek medical treatment. [I am not a worm specialist, nor a medico.]

Freezing by Liquid nitrogen, or surgical excision are techniques available to the specialists. But not for home experimentation.