destroy filedialog does not clear the memory usage in qml

[qAminzzz]

hi
filedialog uses about 10 mgs and it's not good
so i created file dialog dynamically and after accept file i destroy that
but it didn't clear memory usage of file dialog
why? and what should i do?

thanks in advance

code:

property var fdOpenPicture

            onClicked: // my button's signal
            {
                fdOpenPicture= Qt.createQmlObject('import QtQuick 2.0; import Qt.labs.platform; FileDialog {id: test;
            onAccepted:
            {
                btnSelectPict.icon.source= currentFile;
            }

            onVisibleChanged:
            {
print("Destroy");
                if(!visible) btnSelectPict.fdOpenPicture.destroy();
            }
            }',