One of the major factors of how your credit score is calculated is your capacity. This is the ratio of credit used to the amount of credit that is available. This accounts for 30 percent (almost a third!) of your credit score. For example if you have 5 credit cards with a $1000 limit and you have 3 of them maxed out and 2 of them inactive your capacity would be at 60 percent, $3000 of your $5000 total credit limit. This is not good in the eyes of the lenders and your credit score would suffer because its ideal to be at 10 percent of your capacity.

Remember a credit score is a formula measuring your ability to pay back your debts and obligations. If you have a high capacity and little room left for your maximum then your ability to pay back your obligations is viewed as more limited.

So in the example above, lets say you decide to close the 2 inactive cards for whatever reason. Nowadays, the credit card companies will charge a fee to inactive cards so a lot of people are now closing their inactive accounts. Well unfortunately, they are killing their credit score. If you are maxed out on three cards and you close the other 2, guess what, you are now at 100 percent capacity because your total credit limit is now $3000 instead of $5000. I know from personal experience this will cause your credit score to plummet.

My advice ? Don’t close your inactive cards. Use them once a month, maybe for gas, or treat yourself to a latte from Starbucks. Then pay them off immediately so you don’t incur any interest. Do what you can to pay off the cards that are maxed out, or at least get them down to where your balance is under 10 percent of the limit. If you can, try to transfer the balance to a lower interest card, so it can save you a few bucks on the interest. This strategy is sure to improve your credit score because capacity is a major factor, and if your capacity improves, your score improves.

Asking your bank for a credit limit increase on some of your cards isn’t suggested nowadays, this is a strategy that old credit repair people recommended but in today’s economy with the credit crunch, it prompts an account review, which for some quirky reason, may cause the banks to LOWER your credit limit. This would damage your capacity as well.

You are already disciplined enough to not spend on two cards. You are unique in today’s credit crunch world, use your discipline to your advantage, don’t close your accounts. You will be doing more harm to your credit score than good.
Source: https://oknaija.com.ng/how-closing-accounts-can-kill-your-credit-score/