About removing attachments during `edit' of ones posted messages

This is probably supposed to go in some other forum but I hope someone can guide me on this.

I posted a message with an attachment, then noticed after the fact that its the wrong attachment.

I tried to use the edit button to remove the wrong attachment and add the right attachment. But all I do is end up with two attachments.

Using the `Attachment Manager' offers no way to remove an unwanted attachment. And when I just remove the `code' from my message, the original wrong attachment is still there.

Trying to edit again I see the editable window does not show the code for the unwanted attachment and yet when I `save' the edit, there the damn thing is again.

Like a bugger, I can't get rid of it.
Anyone who can offer a technique?