i have a question about credit cards, paying them off, canceling them, and increasing credit score.

i did a balance transfer on a credit card. so i am confused is it better to keep the credit card w a zero balance (cut up in the safe box) or to cancel if since it is paid off? which way is better to the credit reports and fico score?

thanks in advance.. i know that this is the place to find out the correct answers.. you guys are great! keep up the excellent work!