Qt Quick QML Disable Resize and Maximize Buttons Handlers

Hello Everyone I'm newbie to this terms and specially even more to Qt, but slowly i'm making my way in this wonderful language! :D

So my problem is the following one, How can I disable the resize and maximize handles of a Qt Quick QML Game/Application I'm doing...

I have tried some codes like: setSizePolicy( QSizePolicy( QSizePolicy::Fixed, QSizePolicy::Fixed, TRUE )
and this->setSize blababala, but none of them neither works or I'm doing something wrong... like Where do I need to put them, because I'm putting them into the QML plain text section.... or is it
in the CPP file? or H file? Give me a hand on this please.

Thanks in advance to whom it may concern.