Someone told me that if you have a credit card for less than a year and you cancel it (assuming you have zero balance at the time of cancellation), it will NOT affect your credit score, because you had it for such a short period of time. Is this true? I'm trying to find information online that will validate that claim before I proceed.

I got a credit card that was benefitting one of my preferred charities, and then they stopped benefitting that charity, so I don't want to use it anymore. I've only had the card for 5 or 6 months, and always paid it off in full, and I have zero balance on it. Is it safe to cancel, or should I just cut up the card and keep the line of credit open?