Thanks for posting your question in the Microsoft Q&A forum.
To get back to the original search function in Outlook and remove the new Microsoft Search bar, you can follow these steps:
- Open Outlook and go to File > Options.
- In the Outlook Options window, click on the "Search" category.
- Uncheck the box next to "Use Microsoft Search to search across my Office apps and the web"
- Click OK to save the changes.
This will disable the new Microsoft Search experience and revert Outlook back to the classic search functionality, where you can use the regular search box at the top of the Outlook window.
Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful