You will need your control panel login details to complete the following steps
- login to your control panel via the control panel address in your web hosting welcome email usually something like yourdomainname.com.au/cpanel
and enter your control panel username and password as outlined in your web hosting welcome email - locate and click the email accounts icon
- click manage beside the email account you wish to free up space on
- At the next screen under the I Want To Heading
- click free up email storage
- This will list each folder used for email storage Inbox, sent etc
- Click the manage link next to each folder
- Choose the date range to delete email for e.g one year or older
- Click Delete permanently
Do the same for any custom folders that you have created.