Spams and meaningless comments are common in all WordPress sites. Generally what actually happen is you approve right comments and ignore spams etc and in this way after some time you create a big collection of pending comments. Here is a quick and easy way to delete all pending comments from your WordPress site.
Although WordPress provides you a feature of filtering pending comments and deleting them is bulk but what I am here discussing needs only one click and all pending comments are gone.
Install and activate Delete Pending Comments plugin in your WordPress site. After activation visit its page from your Dashboard -> Comments -> Delete Pending Comments. Now all you have to do is click the button “Delete PendingComments’ after copy-pasting the confirmation text in the given text box, see the given screenshot. Best plugin for the victims of spammer attacks.