Delete my iCloud account
There is no charge for iCloud/AppleID. Just remove your credit card, end all subscriptions, cancel any paid storage upgrades and you’re set.

Set a very secure password and be sure you download everything you care to ever have and consider if you want that account back, it’s best to write down the security questions and answers and password just in case.

Once you sign out of all devices except one, you can delete everything at https://icloud.com and then Apple will delete all your files from their servers. Then remove the account from the last device and walk away from that account.