SQLite database close issue

#!/usr/bin/env python
# coding=utf8

"""
    See: http://diotavelli.net/PyQtWiki/Removing a database
         https://qt-project.org/doc/qt-4.8/qsqldatabase.html#removeDatabase
         https://bugreports.qt-project.org/browse/QTBUG-1528
         http://lists.trolltech.com/qt-interest/2008-04/msg00627.html

         http://sqlite.org/c3ref/finalize.html
"""
import os
import sys
import shutil

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtSql import *

import ui_mainwindow


class MainWindow(QMainWindow, ui_mainwindow.Ui_MainWindow):
    """ Main application.
    """
    def __init__(self, parent):
        """ Initialise the MainWindow.
        """
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)

        database = QSqlDatabase.addDatabase('QSQLITE', 'payroll_connection')
        database.setDatabaseName('payroll.db')
        database.setConnectOptions('SQLITE_BUSY_TIMEOUT=6')
        database.open()

        model = QSqlTableModel(self, database)
        model.setTable('tempEarnings')
        model.setEditStrategy(QSqlTableModel.OnFieldChange)
        model.select()

        self.tableView.setModel(model)
        self.tableView.show()


    @pyqtSignature('')
    def on_savePushButton_pressed(self):
        model = self.tableView.model()
        model.select()
        model.submitAll()
        model.query().finish()
        del model

        self.tableView.setModel(None)

        database = QSqlDatabase.database('payroll_connection')
        # No transactions.
        commit = database.commit()
        print 'commit:', commit
        database.close()
        print database.lastError().text()

        #driver = database.driver()
        #print driver.lastError().text()
        del database

        QSqlDatabase.removeDatabase('payroll_connection')
        #os.remove('payroll.db')
        sys.exit(1)

        #QFile.remove('payroll.db')
        #shutil.copy('payroll.db.new', 'payroll.db')
        #
        #self.database = QSqlDatabase.addDatabase('QSQLITE', 'payroll_connection')
        #self.database.setDatabaseName('payroll.db')
        #self.database.setConnectOptions('SQLITE_BUSY_TIMEOUT=6')
        #self.database.open()
        #
        #model = QSqlTableModel(self, self.database)
        #model.setTable('tempEarnings')
        #self.tableView.setModel(model)
        #model.select()


if __name__ == '__main__':

    app = QApplication(sys.argv)
    form = MainWindow(None)
    form.show() #Maximized()
    sys.exit(app.exec_())