When you record information in CellViz, all collected cell signal and location data is stored locally on your device.  You can choose to email yourself these records in CSV and KML formats.  CellViz does not share any information about you or your device with anyone else - there is no CellViz server.  If you wish to delete the data you've collected with the app, simply select "Settings->Show Test History->Delete all", or uninstall and reinstall the app.