Why can't I downgrade my storage options on iCloud?

I am aware of how to downgrade my storage plan on iCloud. I follow all of the steps under System Preferences. When I get to enter my Apple ID-nothing happens. My password gets deleted and I enter it again- same thing happens. I thought at first my password was wrong so I changed it. Nothing-same thing. I restarted my computer-and same thing once I hit that spot to re-enter my password. So I just changed it again and same thing. I do not want to have to pay for storage as I am not using it. Can anyone please help? I am feeling as though I have to pay for it at this point, not very happy with Apple.

Thanks,

Emily