Do a search before you make a new topic, this has been asked before: http://wordpress.org/support/topic/93973?replies=20
To mass delete all comments:
Login to PHPMyAdmin to the corresponding database of your WP Installation. You should see a list of the different tables.
Find wp_comments in that list of tables and click on Empty.
Remember that this will delete ALL COMMENTS SINCE YOUR BLOG’S INCEPTION.
If you don’t want to do that, then you’ll have to hunt up a forum or list for mysql/phpmyadmin and get someone to write you a specific query to do exactly what you want and nothing more.
[If this were me, I’d make redundant dumps of the database (backups). Then I’d open the sql file in notepad2 and truncate the comments table manually, then drop the table from the database online and query the truncated table back in.]
Alright, nevermind what I said..this will delete just the comments that haven’t been approved.
DELETE FROM wp_comments WHERE comment_approved='0';
If you want to delete the ones that have been marked as spam, you can use DELETE FROM wp_comments WHERE comment_approved='spam';
Terrific, thank you very much.
