I need to cancel my subscription

See this Apple article: Downgrade or cancel your iCloud+ plan

Downgrade or cancel your iCloud+ plan - Apple Support (PH)

or

Check your mail box and click the last Apple invoice you have recieved for you iCloud+ plan. 

Then scroll down & see:

👉 If you have any questions about your bill, contact support. This email confirms payment for the iCloud+ plan listed above. You will be billed each plan period until you cancel by downgrading to the free storage plan from your iOS device, Mac or PC.

Read this support article about how to downgrade or cancel your iCloud+ storage plan on an Apple mobile device, a Mac, or a PC. --> Downgrade or cancel your iCloud+ plan - Apple Support