Microsoft Outlook will automatically provide a list of email addresses as you type them in the To: field when composing an email. If you want to clear this list, follow these steps.
Delete Individual Email Addresses
You can delete individual email addresses from the Auto-Complete list by typing the email address into the To: field when composing an email. When the address appears, select the “X” next to it and it will be removed.
Last Update: November 5, 2018