code: public void deleteSharedProjectGroupLink(int groupId, int projectId) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + projectId + "/share/" + groupId;
          retrieve().method(DELETE).to(tailUrl, Void.class);
      }
docs: Delete a shared project link within a group.
  
  @param groupId   The group id number.
  @param projectId The project id number.
  @throws IOException on gitlab api call error