You can clear the autocomplete list within Outlook by following the below steps:
1) Within Outlook, go to File then Options.
2) On the left pane, select 'Mail'
3) Scroll down to the subsection titled 'Send messages'
4) Click 'Empty Auto-Complete List'
5) Click Yes to confirm the action
6) This will then remove any auto-complete entries from Outlook.
If you need any assistance with this, feel free to give our SpiderTech support team a call on 01179330573.