Try the MCPR removal tool linked in the Useful Links at top of this page.
How about a somewhat similar question from a different angle...
I'm about to replace hard drive in my computer. I will want to re-install the Security Center product with the license provided with my Cox High Speed Internet service. But I don't want re-installing the software to count 1 more toward the 3 PC license maximum (I need all 3) -- I just want to reuse same license instance that I was already using on the hard drive that I'm about to replace. How do I make sure that I simply reuse the same license instance when I re-install the software?
It shouldn't effect the number of licenses you have but that is best sorted out by Customer Service linked under "useful Links" at the top of the page if you have any problems. Best to phone them or use the online chat.