Delete Autocomplete Addresses in Microsoft Outlook

Create a new email message in Outlook.

Start typing the name or address you want to remove.

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Use the down arrow key to highlight the desired (undesired) entry.

MS Outlook Remove Image Two

Press Delete Key on your keyboard.

For more control over Outlook's email address auto-complete file, try a tool like Ingressor.

You can also stop Outlook from suggesting email addresses as you type:

Select Tools | Options... from the menu.

Go to the Preferences tab.

Click E-mail Options....
Now click Advanced E-mail Options....

Make sure Suggest names while completing To, Cc, and Bcc fields is not checked.

Click OK.

Click OK again.

Click OK once more.