This article explains how to delete an address from the Outlook AutoComplete list in Microsoft Outlook 2019, 2016, 2013, and 2010. It includes separate instructions for Outlook 2007 and Outlook Online.

Outlook remembers every address you enter in the To, Cc, and Bcc fields of an email message. Then, when you type the first few letters of a name or email address, Outlook automatically suggests contacts that match. If Outlook remembers mistyped or old contacts that you don't want to appear in the autocomplete list, delete those entries.

To remove a single contact from the auto-complete list:

Create a new email message.