i need to cancel my I cloud account

I’m going to guess you mean to downgrade your iCloud storage subscription, and not cancel (delete) your Apple ID and its associated iCloud access. Both are possible.

Tap on each of the following two blue-text links for info on reducing your iCloud storage to the default 5 GB plan.

Manage your iCloud storage - Apple Support

Downgrade or cancel your iCloud storage plan - Apple Support

If I’ve guessed wrong and you were looking to cancel (delete) an Apple ID, let us know and I’ll post details for that.