How can I cancel my subscription to this software, I pay by PayPal, and do not use the software, and do not want to keep paying for it.
Which software are you referring to? Are you a Creative Cloud user looking to cancel your personal subscription, or are you looking to cancel a Marketing Cloud contract?
It sounds like you may be looking to cancel your personal Creative Cloud subscription. I'm not personally familiar with the process, but I did find the following help article that may be of some help.