How to Clean Up Your Outlook Inbox

  1. From your inbox (or the desired email folder), click on Home > Clean Up.
  2. There will be the option to Clean Up Conversation, Clean Up Folder, or Clean Up Folder & Subfolders. Click on the desired choice. 
    1. For more instructions on Conversation Clean Up, see "Use Conversation Clean Up to delete redundant messages" directly from Microsoft: https://support.office.com/en-us/article/use-conversation-clean-up-to-delete-redundant-messages-70179d54-fa57-48ce-95fd-416d72e5ccd4?wt.mc_id=otc_tips

Outlook automatically moves redundant, read messages to Deleted Items folder. Clicking on Clean Up Folder will not remove unread messages.