You can remove the mail account from iOS devices under Settings/iCloud (disable the Mail button).
If you want to stop receiving mail to one address entirely without removing the account, you can also create a forwarding rule. Login to iCloud.com, goto Mail and click the settings button on the bottom left. Then under "Rules" add a rule for mails that are "addressed or Cc'd to" the email address in question, with "Move to Trash" as the action. This way, all mails sent to this address will be discarded immediately.