Deletes a date type from the database.
$type: The machine-readable name of the date type.
function system_date_format_type_delete($type) {
db_delete('date_formats')
->condition('type', $type)
->execute();
db_delete('date_format_type')
->condition('type', $type)
->execute();
db_delete('date_format_locale')
->condition('type', $type)
->execute();
}