No, you must continue to treat them.
You cannot discontinue needed treatment just because a patient smells bad, but you can take steps to improve the situation. Have a discussion with the patient. Describe the issue as objectively and respectfully as possible and offer a suggestion. For example, your clothing smells strongly of cigarettes and it is impacting my ability to provide treatment to you. Is it possible for you to bring some freshly washed clothes to change into when you arrive for your appointment?
For further details, the Providing or Refusing Care Standard outlines the criteria for discharging patients.
Read the Standard