Unset Generic Variables set in a Template

I am used to programming in PHP and one of the things I practice is always clearing a variable as soon as I am done using it on any given page so that it does not inadvertently affect anything else on down the page.  So for example, if I use ##SET[GenVar=12]## in the header template and I only intended to use that variable in the header template, I would want to clear it at the end of the header template so that I did not inadvertently affect anything, say in the product details template.

 

I was looking for a way to clear the generic variables within a given template after I was done using it, even before the page was rendered to the customer, but there is no such option at this point.  It would be nice to have an ##UNSET[GenVar]## option.