code: public ItemRequest<CustomField> delete(String customField) {
      
          String path = String.format("/custom_fields/%s", customField);
          return new ItemRequest<CustomField>(this, CustomField.class, path, "DELETE");
      }
docs: A specific, existing custom field can be deleted by making a DELETE request on the URL for that custom field.
  
  Returns an empty data record.
  
  @param  customField Globally unique identifier for the custom field.
  @return Request object