I kept mine open. It has a credit limit of $9900. I paid for half of my motorcycle in cash, so about $5k was put on the card. I paid off the balance in 6 months, so it's been zeroed out for the last 8 months.
Recently I tried applying for a credit card with them since they have no foreign transaction fees. My credit score of 812 was still denied since the high credit was $5k. I wrote back explaining the situation. They pulled my credit report again (score dropped down to 805), and denied credit again with the same reason. It doesn't matter if the Kawasaki card was paid off long ago.
I tried contacting their Twitter account. They were absolutely no help. They even said they aren't credit specialists and that I should go find one to answer my questions.
If you don't plan on using it again, you might want to consider canceling the Kawasaki card so that you can get credit from Capital One in the future. Otherwise, consider Capital One as an unwilling creditor in the future. I'm currently debating closing mine. I only financed half of my bike because I thought it would be a regular vehicle loan (not a credit card) and figured it would help my credit. I don't think there's any way to get Capital One to adjust the high credit limit amount or use the card balance instead.
I would write them again, but I figure they will just pull my credit report again and deny my application a third time. I thought my excellent credit rating would have no issues getting credit card.