1 – Login to your Directadmin.

              https:/#domain#:2222/

2 – Under E-Mail Management section, go to E-Mail Accounts

3 – Tick the email account you would like to empty the inbox.

4 – There is a dropdown list on the right of ‘Purge From’ button, select ‘Inbox’.

5 – You can choose to remove email from when based on the option.

6 – Lastly, click ‘Purge From’ to remove emails under the account.