I have a simple AudioRecorder in my QML-application. As there is no QML-control directly available for recording Audio with Qt 5, I made an own class derieved from QAudioRecorder :

#include 
#include 
#include 
#include 
#include 
#include 

class AudioRecorder : public QAudioRecorder
{
    Q_OBJECT
    QML_ELEMENT

public:
    AudioRecorder(QObject* parent = Q_NULLPTR) : QAudioRecorder(parent)
    {
        QString d = QStandardPaths::writableLocation(QStandardPaths::StandardLocation::MusicLocation);
        if (!d.isEmpty())
            setOutputLocation(QUrl::fromLocalFile(d));
    }
};

In my app I have a simple button which is being used for starting and stopping the recording:

// My own QML element
AudioRecorder {
    id: audioRecorder
}

Button {
    id: recButton

    onClicked: {
        if (audioRecorder.state === MediaState.StoppedState)
            audioRecorder.record()
        else if (audioRecorder.state === MediaState.RecordingState)
            audioRecorder.stop()
    }
}

After recording, there is another button appearing which can be used to remove the created audio-file. I remove the file with a helper-class which provides some functions I cannot access from QML directly:

Button {
    id: remButton
    visible: audioRecorder.state === MediaState.StoppedState
    onClicked: QMLHelper.removeFile(audioRecorder.actualLocation)
}

class QMLHelper : public QObject
{
    Q_OBJECT
    QML_ELEMENT
    QML_SINGLETON

public:
    QMLHelper(QObject* parent = Q_NULLPTR) : QObject(parent) { Q_UNUSED(parent) };

    Q_INVOKABLE bool removeFile(const QString& path)
    {
        if (!path.isEmpty())
        {
            QFile f(path);
            bool r = f.remove();
            qDebug() << r << ": " << r.errorString();
            return r;
        }
        return false;
    };
}

The output when I try to remove the file is:

false: The process cannot access the file because it is being used by another process.

Why is the QAudioRecorder not releasing the file after calling stop() ? How can I release the file to remove it?

Remark: I tried it with an QML videoRecorder, and here it does work without problems:

Camera {
    id: camera
    videoRecorder {
        id: vr
    }
}

Button {
    id: vidButton
    visible: camera.videoRecorder.recorderStatus !== CameraRecorder.UnavailableStatus
onClicked: {
    if (camera.videoRecorder.recorderState === CameraRecorder.StoppedState)
        camera.videoRecorder.record()
    else if (camera.videoRecorder.recorderState === CameraRecorder.RecordingState)
        camera.videoRecorder.stop() 
}

Button {
    id: vidRemButton
    visible: camera.videoRecorder.recorderState === CameraRecorder.StoppedState
    onClicked: QMLHelper.removeFile(camera.videoRecorder.actualLocation)
}

Output:

true