How do I downgrade my extra storage plan? I no longer have an Apple phone. I do not need it anymore

1. Go to Settings > [your name] > iCloud > Manage Storage or iCloud Storage.
2. Tap Change Storage Plan.
3. Tap Downgrade Options and enter your Apple ID password.
4. Choose a different plan.
5. Tap Done.

If you can't click Done, make sure you are signed in with the same Apple ID as your iCloud storage plan. You can also try following these steps on a different device. If you still need help, contact Apple Support.