How to delete a database in WebSQL programmatically?

I am new to Web SQL database and I use it to save data in a local database in a web page.

　I can create a database by

var db = openDatabase('database', '1.0', 'my database', 2 * 1024 * 1024);

　and I can create a table by doing this

db.transaction(function (tx) {
  tx.executeSql('CREATE TABLE IF NOT EXISTS mytable (blah,blah)');
});

　I can delete the table by

db.transaction(function (tx) {
  tx.executeSql('DROP TABLE mytable');
});

　but is there a way to delete the database programmatically?