I have a QBoxLayout and I want to delete some widget from it. That widget was created like this:

QWidget qw;

QComboBox combo=new QComboBox(&qw); //parent the principal widget
QComboBox combo2=new QComboBox(&qw);
...

center_layout->addWidget(&qw);

With the last instruction the widget appears perfectly in the window, but when I try to remove it with
center_layout->removeWidget(&qw);
it doesn't work. The widget still appears in the window and I can interact with it.
So.. how can I remove this widget completly?

Jaime