A wart on the top of the foot really should be looked at by your doctor to make sure it is a wart.
If it is then using a freeze off product can work well to elimnate this growth. Follow directions carefully when using this sort of product.
First be sure it is only a wart.Warts can be treated by various treatments available from your Chemist. Failing this Chiropodists or Doctors can use freezing or diathermy type procedures.
Medically, the best way is to go to a doctor and have the wart frozen off, but the best home remedy is to put a banana peel (the inside part) on top of the wart and wrap the foot with duct tape to hold the banana peel in place.
This may be a Plantars' wart and if it is, you will probably need surgery to remove it. This type of wart tends to have long roots and the wart will be cut out.