How do I disable iCloud on my Apple device?

Which "Apple device"?

You have to turn off individual components. Read this support article about how to change your iCloud feature settings [iOS, Mac, PC] - Change which apps sync and store data with iCloud - Apple Support - "'When you turn off an iCloud feature on a device, information stored only in iCloud for that feature is no longer available on the device. If you turn off Mail, Contacts, Calendars, Notes, Reminders, or iCloud Photos on just one device, you can still view and change your information on iCloud.com and on another device you set up for that feature."

Adam1989A wrote:

I want to delete my iCloud account

There is no iCloud Account, there is an Apple Account (formerly known as an Apple ID) with some amount of iCloud storage associated with.

You can delete an Apple Account, though you will need to make absolutely certain here are no uses of this account t anywhere, as those uses can be permanently bricked. Deleting an Apple Account t associated with Activation Lock will brick the devices, absent original purchase receipts. In general, deactivating an Apple Account is very much preferable to deleting, too.

If you are referencing Activation Lock here, that’s intended as a theft deterrent, and intentionally difficult to bypass. You’ll either need the assistance of the person holding the Apple Account associated with the Activation Lock, you’ll need to regain your Apple Account, or you’ll need the original purchase receipt from Apple or an authorized reseller.

Turn off every app that uses iCloud in Settings. How you do that will depend on your device. There is no master switch to turn iCloud on/off, but you don't have to use it for any app.

Adam1989A wrote:

I want to delete my iCloud account

It is unclear what you are saying.

Are you asking us how to

• Reduce your iCloud data usage so that you don't have to pay for extra iCloud+ storage? (See: Downgrade or cancel your iCloud+ plan - Apple Support)
• Delete your Apple Account entirely, in which case you will not be able to download things from the App Store, and your device won't be protected by Find My?
• Get into a phone that's Activation Locked to another person – a previous owner? (See: The All Too Common SAD Reality of Buying a Used iPad/iPhone – Apple Community)