Windows Explorer shows suggestion pop-ups as users type into the Search Box. These suggestions are based on their past entries into the Search Box. But if you wish, you may disable suggesting of recent queries for the Search Box and prevent entries into the Search Box from being stored in the registry for future references.
Turn Off Display Of Recent Search Entries In The Windows Explorer
To do so, type gpedit.msc in the Start search and hit Enter to open the Group Policy Editor.
From the left pane navigate to the following directory:
User Configuration > Administrative Templates > Windows Components > Windows Explorer
Now from the main window, right-click Turn Off Display Of Recent Search Entries In The Windows Explorer key and select Edit.
Select Enabled and click OK.