I'm no expert, but I think it would hurt your credit score to have it lowered. At this point, you're using 15.625% of your available credit. If you had it lowered to $10,000, you'd be using 50% of your available credit. I think one of the big things that helps your credit score is not using anywhere near your available credit, so obviously, having a lower debt:credit ratio is better.
I could be wrong.