I want to cancel my iCloud storage subscription

So where is your iPhone?

Login to your iCloud account from a computer or other device...

https://www.icloud.com/

Select Manage Apple Account (upper right hand corner of webpage), select Subscriptions, select iCloud and cancel from there. No one here can cancel any subscription for you. Sorry.

Doesn’t matter. No one here can help you. You are responsible for managing your subscriptions. Use the link I provided to cancel your subscription. If you have forgotten your Apple Account password read the instructions in the links below.

If you forgot your Apple Account password - Apple Support

https://iforgot.apple.com/