This link is for withdrawal of application for family sponsorship:
http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=732&top=14
If it's any consolation, I'm still waiting as well. Our app is so simple. Canadian married to an American. We've been together for almost six years. I own my house (outright come August!) and I've been at the same job for years. I thought we'd be well into the process by now. I don't understand why it's taking so long to just get SA. One person in the US applicants thread told me they sent their app in October and didn't get SA until January. Said they were freaking out. That gives me a bit of hope and I really, really need it right now. This is supposed to be an exciting and happy thing and I am just so frustrated, annoyed, discouraged, and kind of scared. Ugh.