Your call to close or keep it open. People will suggest what they would do but you need to consider your own preferences and priorities as well as credit/scoring considerations. I think I recall reading a thread that there was a scoring benefit to having less than 50% of your cards reporting a balance but you'd need to confirm that.
Closing will immediately impact utilization. You can do the math before and after to see the impact to help you decide. AAoA is not immediately impacted.
If you can't or won't continue to actively monitor the card for fraud then don't SD it.
JonE wrote:It will affect utilization, but if your limits are already high enough it should be a wash.
It's not just a matter of limits but balances as well. Anyone making such a decision should just do the math. It's not difficult: balance(s) / limit(s)