The answer is a simple line of SQL. Simply run this SQL query on the offending table (in this case ‘warranty_customers’ is the table and the bad entries range from id 279 to 1400). Simples!

DELETE FROM  `warranty_customers` WHERE  `warranty_customers`.`id` >279 LIMIT 1400 ;

If you are using WordPress you can use the line in PhpMyAdmin:

DELETE FROM wp_comments WHERE comment_approved = 0

or if you are using Askimet (where the value of approved may be set to ‘spam’) use this line in phpMyAdmin:

DELETE FROM wp_comments WHERE comment_approved = ‘spam’