Using Classic Outlook on Windows for personal email, calendar, and contact management
There is a Feature Request that you can Vote for to revert this change:
Return ability to delete individual auto-complete suggestions for email recipients
https://feedbackportal.microsoft.com/feedback/idea/97490d3b-7d45-f111-9a91-000d3a05c4f5
(You must "Sign In" at the top right of the Feedback page before you can vote).
To salvage any email addresses in your Autocomplete List you want to keep before you clear it:
See the Answer by "Hornblower409 May 1 2026" How to convert your Autocomplete List to Contacts and erase the List in: https://learn.microsoft.com/en-us/answers/questions/5871874/manually-removing-an-email-address-from-the-sugges?orderby=newest&page=1#answers