code: public void deleteProjectMember(Integer projectId, Integer userId) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + projectId + "/" + GitlabProjectMember.URL + "/" + userId;
          retrieve().method(DELETE).to(tailUrl, Void.class);
      }
docs: Delete a project team member.
  
  @param projectId the project id
  @param userId    the user id
  @throws IOException on gitlab api call error