You cannot delete bounced or unsubscribed emails from CRM. For Bounced Email, you can only remove or update the email.
You can do this by going to Campaigns>>Suppression Lists.
To remove, you may select which ones to be removed by clicking the box next to the names and click the Remove
To update the email, click the 3-dot icon on the right of the contact and click Update Email. This will lead you to the
contact’s profile. Key in the new email address and click the Save button.