How to remove the default menu on the left side of the title bar - Qt?

[TheIndependentAquarius]

Qt :: WindowFlags flags = 0;

// Makes the Pomodoro stay on the top of all windows.
flags |= Qt :: WindowStaysOnTopHint;

// Removes minimize, maximize, and close buttons.
flags |= Qt :: WindowTitleHint | Qt :: CustomizeWindowHint;

window->setWindowFlags (flags);
window->setWindowTitle ("Failing to plan is planning to fail");
This removes minimize, maximize, and close buttons. The default menu on the left is still there. How to get rid of that?

I want the title bar to be there, but just want the menu to be removed.

Default menu contains: Minimize, Maximize, Move etc options.

[Spitfire]

On what system?

this->setWindowFlags( Qt :: WindowStaysOnTopHint | Qt::WindowTitleHint | Qt::CustomizeWindowHint );
works as you want on W7 and Ubuntu.