Few days ago i decided to experiment on something and i ended up importing wanted and on want mail address to my server and when i try to delete, there was no option to delete the the addresses at once until i figured it out after some minutes i tried delete them one by one but now i found a way to delete any email address associated with your domain name if only you don't need them anymore.How to delete thousands of emails at once from your server in Cpanel
To delete all the unwanted email addresses associated with you domain simply follow this steps below:
Deleting in Cpanel simply login and go to: File Manager > mail > domain.com > username > inbox > Delete File
In some host you can see the full list of all the email addresses simply by going to File Manager > Mail
to view and delete all the associated email addresses at once.
Secondly you can as well delete it through SSH by following this steps below
cat /dev/null > inbox
The above details will take you where you will be able to clear your inbox and delete any file you don't need again.