To hide a contact from auto-complete:
- Go to Settings | Groups & Contacts and tap Edit next to the contact. This opens the contact's page.
- Turn on Hidden in autocomplete.
The contact stops appearing in the suggestions while you type an address in an email, but it is not deleted. Turn the switch off again whenever you want the suggestions back.
From the Contacts tab, you can reach the same page by tapping the contact and then their picture at the top.
Is the suggestion a mistyped address rather than a real contact? See How Do I Fix a Typo in a Saved Contact or Autocomplete?
