Clear Auto Complete
https://www.youtube.com/watch?v=LNPHm3s5SoA
To remove entries from the AutoComplete cache one entry at a time, follow these steps:
- Open a new email message.
- Type the first few characters of the AutoComplete entry that you want to remove.
- When the entry appears in the list of suggested names, move your mouse pointer over the name until it becomes highlighted, but do not click the name.
- When the "X" icon appears next to the highlighted name, click X to remove the name from the list, or press the Delete key on the keyboard.
To disable AutoComplete or clear your AutoComplete list entirely, follow these steps:
- In Outlook 2010/2013/2016, click the File menu and select Options.
- In the Outlook Options window click the Mail tab.
- Scroll down to Send messages. Uncheck the Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines box.
To clear the AutoComplete list, simply click the Empty AutoComplete List button. You’ll see a confirmation window about clearing the AutoComplete list, click Yes.
Outlook AutoComplete should be completely disabled and any history that was in the auto-complete list should be completely erased (if you clicked the clear auto complete button).