I just open the old meeting, select and delete the attachment, then save and
close.
When in table view, the attachments field should already be in the default
setting (represented by the paper clip). If it's not showing, you can
right-click on the field title bar, select "Field Chooser," then drag and
drop "Attachment" onto your title bar.
I don't know of any way to delete all old attachments at once if that's what
you're asking.
