The simplest and most effective remedy is baked onion. Bake a small onion, remove the centre and put the onion on the verruca. Allow the onion to foment to your tolerance limit. Leave it in place overnight. Repeat each day for 3-5 days.
Another good remedy is tincture of thuja, which you can buy from any healthfood store or homoeopathic chemist. Apply before going to bed. It will help to increase the acidity of the skin. Remember that for a healthy balance the skin needs to be acidic and the inside of the body slightly alkaline.
Verrucas on the feet are particularly difficult to deal with because pressure is applied to them constantly. The only solution is to have a chiropodist remove the root.