There are lots of coments awaiting for moderation in WordPress Dashboard, you can’t delete them one by one, or one page list with 20 comments, well, login phpmyadmin;
Click the label “SQL” ,run the following SQL command:
delete from wp_comments where comment_approved = ‘XXX’
XXX in three values:
spam: comments in trash
0: comments in moderation
1: comments approved
then click “Run” button to delete the three type of comments.