If you use a module, do you read the documentation?
It's right there on cpan: CGI::Session

delete()

    Deletes a session from the data store and empties session data fro
+m memory, completely, so subsequent read/write requests on the same o
+bject will fail. Technically speaking, it will only set object's stat
+us to STATUS_DELETED and will trigger flush(), and flush() will do th
+e actual removal.
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Update: Whoops, i did not read your question well enough, sorry :$.

Yes you can, just re-create the cookie and delete it (but the answer was already given.