int MainWindow::botondirecto()
{
    main = new MainWindow(); <<< make new window . its not the old one from botonbarrido()
    ui->menubar->removeEventFilter(main); <<< remove the filter but did we ever put one On as main seems new to me

So did i drink from the night pot or
did you mean to use removeEventFilter on the "main" we created in botonbarrido() ?

Also do notice if you are using my code for the filter, then you can
call
SweepModeToggle(true) to have it filter and SweepModeToggle(false) to allow all.
So you dont have to go and install and remove it.

But when I click Direct mode where I uninstall the filter but it doesn't work for me and the menus are still blocked.

void MainWindow::on_actionModo_Barrido_2_triggered()
{

    modoBarrido = 0;
    topFiller = new QWidget;
    QVBoxLayout *box =  new QVBoxLayout;
    QPushButton *mododirecto = new QPushButton(tr("ModoDirecto"));
    QPushButton *modobarrido = new QPushButton(tr("ModoBarrido"));
   // layout->setContentsMargins(0, 40, 40, 40);
    box->addWidget(mododirecto);
    box->addWidget(modobarrido);

    topFiller->setLayout(box);
    topFiller->setGeometry(500,200,400,400);

    topFiller->setStyleSheet("background-color:rgb(23, 255, 240)");
    topFiller->show();

    connect(mododirecto,SIGNAL(clicked()),this,SLOT(botondirecto()));
    connect(modobarrido,SIGNAL(clicked()),this,SLOT(botonbarrido()));

}
int MainWindow::botonbarrido()
{
    main = new MainWindow();
    modoBarrido=0;
    if(modoBarrido==0){

        timeoutMenuPrincipal();
        topFiller->close();
        ui->menubar->installEventFilter(main);

    }

    return modoBarrido;

}

int MainWindow::botondirecto()
{
    main = new MainWindow();
    ui->menubar->removeEventFilter(main);
    modoBarrido=1;
    if(modoBarrido==1){
        Highlight->~QRubberBand();
        timer.stop();
        timer2.stop();
        timer.disconnect(&timer, SIGNAL(timeout()), this, SLOT(BarridoMenuPrincipal()));
        timer2.disconnect(&timer2, SIGNAL(timeout()), this, SLOT(BarridoSubMenu()));
        topFiller->close();

    }
    return modoBarrido;
}

Hi
You can use
https://doc.qt.io/qt-5/qwidget.html#grabMouse
to have all events go to some widget, effectively making it impossible to click on anything else.
However, it offers no control of what can is eaten. and if you fail to to ungrab as many times as you grab,
it will still be grapped. Also docs says:
"Warning: Bugs in mouse-grabbing applications very often lock the terminal. Use this function with extreme caution, and consider using the -nograb command line option while debugging."

Not the best solution, imho.

So another solution is to use an event filter.

// the filter class
#include <QEvent>
#include <QMouseEvent>

class MouseEater : public QObject
{
    Q_OBJECT
    bool sweepmodeActive{0};
protected:
    bool eventFilter(QObject *obj, QEvent *event)
    {
        if (event->type() == QEvent::MouseButtonPress || event->type() ==  QEvent::MouseButtonDblClick) {
            QMouseEvent *mp = static_cast<QMouseEvent *>(event);
            qDebug() << "MouseButtonPress detected" << sweepmodeActive;
            if ( mp->button() == Qt::LeftButton  ) {
                return sweepmodeActive; // say we handled it (true)
            }
        }
        return QObject::eventFilter(obj, event);// normal forward
    }
public slots:
    void SweepModeToggle( bool status)
    {
        sweepmodeActive = status;
        qDebug() << "sweepmode" << status;
    }
};

// in main window 
 MouseEater *me = new MouseEater();
 connect(ui->pushButton, &QPushButton::toggled, me, &MouseEater::SweepModeToggle ); // to toogle sweep mode
 ui->menubar->installEventFilter(me); // put filter ont he menubar

the result is this.

Why not just disable the menu ?