In the short term, any new account will have a mostly negative effect on your score. You get an inquiry (no changing that), and your AAoA will go down (a little or a lot depending on how many other accounts you have). Even if you close right away, it will still show as a new account on your reports, and stay their for 10 years from the point you close it. The positive effects would be high limits available to help buffer utilization, and over time the AAoA hit will become an AAoA boost as the card ages.
So as others have suggested, you might as well keep it for now since you're already subjected to the negative effects. Since there's no fee, I'd suggest just waiting a year to see if you get any use out of it, and if not, go ahead and close it if you don't want to keep track of it.
