Cancelling the Realplayer Superpass is one of the toughest things to do. You call their “cancellation number” and listen to nice elevator music for over an hour. It would even drive me to cursing.
Do yourself a favor, call the Customer Support number and press #3 to get a live person within a couple of minutes. They can cancel you with no problem.
The number is 1-866-585-4541.
Call between Monday - Friday, 9:00 am to 9:00 pm - Eastern Time or Saturday - Sunday, 10:30 am to 8:00 pm - Eastern Time.
You will also want to check the comments below because there's a great tip in the second one.