code: public ApiResponse<Void> deleteCharactersCharacterIdMailLabelsLabelIdWithHttpInfo(Integer characterId,
              Integer labelId, String datasource, String token) throws ApiException {
          com.squareup.okhttp.Call call = deleteCharactersCharacterIdMailLabelsLabelIdValidateBeforeCall(characterId,
                  labelId, datasource, token, null);
          return apiClient.execute(call);
      }
docs: Delete a mail label Delete a mail label --- SSO Scope:
  esi-mail.organize_mail.v1
  
  @param characterId
  An EVE character ID (required)
  @param labelId
  An EVE label id (required)
  @param datasource
  The server name you would like data from (optional, default to
  tranquility)
  @param token
  Access token to use if unable to set a header (optional)
  @return ApiResponse&lt;Void&gt;
  @throws ApiException
  If fail to call the API, e.g. server error or cannot
  deserialize the response body