code: public boolean deleteJiraService(Integer projectId) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + projectId + GitlabServiceJira.URL;
          return retrieve().method(DELETE).to(tailUrl, Boolean.class);
      }
docs: Remove all previously JIRA settings from a project.
  https://docs.gitlab.com/ce/api/services.html#delete-jira-service
  
  @param projectId The ID of the project containing the variable.
  @return
  @throws IOException on gitlab api call error