I am trying to cancel iCloud storage subscription and cannot access app to cancel

Cancel upgraded iCloud storage by downgrading to the free 5GB plan. See instructions in: https://support.apple.com/en-us/HT207594

I don’t know what device you are using or what app you are describing unless you mean the settings app on an iOS device, or System Preferences on your Mac, but here are the instructions that explain how to cancel/downgrade iCloud Storage.

Downgrade or cancel your iCloud storage plan - Apple Support

I am trying to cancel my I cloud storage. Please cancel!!!!!

Cancel I cloud storage now, please cancel!!! Reply

Please read this again or for the first time.

Downgrade or cancel your iCloud storage plan - Apple Support

You are not talking to Apple. This is a user to user support forum and we cannot cancel your plan. You have to do it on your own.