Hi Wayne
1) To delete an email from a conference you must be the recipient of the email, i.e. the mail should have been sent to your email ID.
In this case highlight the email in browse window>> go to Record>> click Delete
Mail should disappear
2) If the email was sent to a conference email/group ID then open the email and delete the recipient address from the list and SAVE again
The email will disappear - please check your access to ensure you have full access to read and write to emails
If you wish to delete an email that you sent then find it in your mailbox and delete as per normal above (1) it will then be deleted from your sent main mailbox outgoing mail
Should you have any further questions please don't hesitate to ask :)