curl --request DELETE \
  --url https://api.sendrealm.com/contacts/{contact_id}/audiences/{audience_id} \
  --header 'Authorization: Bearer <token>'

{
  "status": 123,
  "data": {
    "contact_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "audience_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "deleted": true
  },
  "error": null,
  "metadata": null
}