class MyModel: public QAbstractItemModel {
	QList< ClientData > clientData;
public:
	QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const;
	QModelIndex parent(const QModelIndex &child) const;
	bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex());
///... остальные методы
};

QModelIndex MyModel::index(int row, int column, const QModelIndex &parent) const {
	qDebug() << "index" << row << column;
	return createIndex(row, column);
}
QModelIndex MyModel::parent(const QModelIndex &child) const {
	qDebug() << "parent";
	return QModelIndex();
}
bool MyModel::removeRows(int row, int count, const QModelIndex &parent) {
	qDebug() << "remove rows" << row << count << parent;
	beginRemoveRows(parent, row, row+count-1);
	qDebug() << "remove from " << row << "to" << (row+count-1);
	for(int i=0; i<count; i++) {
		clientData.removeAt(row);
	}
	qDebug() << "end remove";
	endRemoveRows();
	return true;
}

	qDebug() << "remove all" << dataModel->rowCount();
	dataModel->removeRows(0, dataModel->rowCount());