Depends. Depend on what type of cancer? Squamous cell, basal cell, skin lymphoma? Etc. Surgical resection if localized on the skin and if indicated. If it is already spreading to distant organ-then systemic therapy ( chemo or other biological agent) will be the option. In certain cancer on the skin -radiation therapy, uv therapy , topical chemotherapy , interferon etc-could be the treatment as well.
Usually excision. Removal of most small skin cancers is curative. This is generally done with surgical excision, although other options exist. Discuss with your dermatologist, primary doctor or plastic surgeon.