I want to purge the number from my account.  I don't want it anymore. 

Google doesn't allow or can't handle that request. 

I do not want a Google Voice number associated with my account.  No company should have a service that can not be canceled completely.

It is almost like being trapped.  Google set the bait with some interesting sounding services, but when those services are tried and not desired; you are trapped because there is no way to get rid of them.