lib/sysrev/sysrevMeta.js
function(user, systemId, cb) {
    if (!_systems[systemId]) { return cb(); }
    var newSystems = _.clone(_systems);
    delete newSystems[systemId];
    fse.writeFileSync(systemsJsonPath, JSON.stringify(newSystems, null, 2), 'utf8');
    _systems = newSystems;
    git.commit(sysRepoPath, 'unregistered system: ' + systemId, user.name, user.email, cb);
  }
function(user, systemId, cb) {
    if (!_systems[systemId]) { return cb(); }
    var newSystems = _.clone(_systems);
    delete newSystems[systemId];
    fse.writeFileSync(systemsJsonPath, JSON.stringify(newSystems, null, 2), 'utf8');
    _systems = newSystems;
    git.commit(sysRepoPath, 'unregistered system: ' + systemId, user.name, user.email, cb);
  }
unregister a system