To mass delete comments in the WordPress admin panel, follow these steps:
Log in to the WordPress admin panel and go to the “Comments” section.
On the comments page, you will see a list of all the comments on your site. You can select multiple comments by clicking the checkbox next to each comment you want to delete.
Once you have selected the comments you want to delete, scroll to the top or bottom of the comments list and look for the “Bulk Actions” dropdown menu.
Select “Move to Trash” from the dropdown menu. This will delete the selected comments from the site.
To permanently delete the comments, go to the trash section and select the comments you want to delete permanently and click on “Empty trash” or you can also select all the comments and delete it once.
Note that deleting comments permanently will remove them from the site permanently and it will not be recoverable.
Additionally, in case you have thousands of comments and you want to delete all of them, you can use a plugin such as “Delete All Comments” or “Bulk Delete” to delete comments in bulk. These plugins will enable you to select and delete comments based on different criteria, such as date, author, and more.
WordPress also has an inbuilt feature to approve, unapprove, mark as spam, move to trash and delete comments in bulk. It can be found by clicking on the checkbox on the top of the comment list, which will give you option to perform bulk actions on selected comments.
It’s always a good practice to take a backup of your website before making any major changes.
You can also go to plugins -> Add new plugin and search the WP Bulk Delete plugin and use that to delete more than the allowed page comments at once.