You can remove all WordPress comments submitted by your users before a specified date.
- Log into phpMyAdmin (cPanel / Plesk / Web Hosting / Managed WordPress).
- Select the database for your WordPress site in the left-hand column.
- Click the SQL tab.
- Enter the following command into the "Run SQL query..." box:
DELETE from wp_comments WHERE comment_date <= 'YYYY-MM-DDHH:mm:ss'
Update the command for your situation as follows:
Warning: If your WordPress database uses custom table prefixes, then you must replace wp_ in each command with the prefix listed in your wp-config.php file.
- Click Go.
More info