How to delete item programmatically?

[Lee Nelson <jld123@pobox.com>]

Hello everyone,

  I would like to be able to delete items from the
cart automatically, with Perl code.  My Perl is 
pretty good, but I'm having some trouble getting
this to work. 

  Do I just need to undef the item?  What's the
syntax please?  

  In case you're curious, I only want one instance
of the item to appear in the cart... If the user
tries to add another, the first should disappear.
I can do this on the form, or from a user tag.  

  I checked back through the mailing list archives,
and couldn't find anything like this.

  Thanks Much,

    Lee Nelson