You may want to keep a single `forEach` call:

```js
    Object.keys(users).forEach(function(nick) {
      var user = users[nick];
      if (user.ws === ws)
        delete user.ws;
      if (user.ws)
        user.ws.send(JSON.stringify({users: _presentUsers(users)}),
                     function(error) {});
    });
```