I'm inexperienced with forms and need to replace an outdated Excel file that
is imbedded within a custom Outlook form that someone built several years
ago.  In Design mode, when I right-click the existing attachment and select
Delete, the entire control box disappears.  

I can add an second attachment by selecting the Insert menu but the old file
is still there.  How do I remove the old one?  It seems simple but it isn't
turning out that way.  Thanks in advance.