Automatically delete a previous version of an item in a SharePoint list when updating a InfoPath 2007 and a SharePoint workflow

Hello,

I have a situation where I use InfoPath 2010 appointment form in a SharePoint 2007 library.  When filling out and saving  the form, the form is uploaded to a SharePoint library, and the appointment is autopopulated in a separate SharePoint calendar.   If  users want to modify their appointment from the InfoPath form in the library, the calendar will display their new appointment.  I used SharePoint designer to create a workflow to do that.  The problem I'm having is this workflow doesn't delete the previous appointment.  How do I do delete that previous appointment?  The calendar will list the new and the old appointment.

The fields I'm using are title, user name, start date and time, and End date and time.

I don't have the ability to understand or write code. 

Does a solution involve creating a Lookup column in the Calendar?

Using: SharePoint 2007, SharePoint Designer 2007, InfoPath 2010.

Thank you,

marty