$result = @mysql_query("DELETE FROM some_table WHERE email_address='$email'");
Delete old records by date
$result = @mysql_query("DELETE FROM messages_sent WHERE created_date < DATE_SUB(NOW(), INTERVAL 30 DAY)"); //Also: //INTERVAL 1 MONTH //INTERVAL 1 HOUR //etc
Truncate is the fastest method to delete all data in a table as the table is dropped and re-creaed.
$result = @mysql_query("TRUNCATE TABLE all_songs");