If that's the case, the $ 500 available credit line on that old card won't have much impact on your credit utilization percentage, and you can safely cancel it. (creditrepairreview.com)
One of the factors influencing your credit score is utilization — that is the percentage of your total available credit line you use. (valuepenguin.com)
This is the amount of debt you're carrying compared to your overall available credit line. (mybanktracker.com)