How to delete all private messages in phpBB3
To delete all private messages from your phpBB3 forum, you need to run two SQL queries. The best way to do this is with phpMyAdmin.
Log in to phpMyAdmin,Â select your phpBB database from the menu on the left and click on the SQL tab. Paste the following commands in the box:DELETE FROM phpbb_privmsgs WHERE `author_id` > 0;
DELETE FROM phpbb_privmsgs_to WHERE `msg_id` > 0;
and click the Go button to execute the queries.
Note that if your forum has a database prefix different than the default phpbb_, you need to replace the prefix in the above queries with your custom prefix so that they can be executed properly.