How to delete Emails listed under ZMail Public Users, Email Module

How to delete Emails listed under ZMail Public Users, Email Module

It isn't possible to delete emails listed under 'ZMail Public Users'.
In contray it's possible to delete emails listed under 'Sent Emails form CRM'.

How can I delete those emails?

Thank you for advice.

@Zoho Support, I created many test emails to check inconsistencies of email integration, I must delete those in any case. Thank you.