How to delete my iCloud account?

Try -- How to delete your Apple ID account - Apple Support.

To truly delete an iCloud account and all its data, you have to delete the AppleID. You cannot delete your AppleID. You have to request Apple do it, as explained in the link zinacef provided. Read that carefully!

I don't know how to delete my account either please help it doesnt help that I'm on a Mac lol please help?