Quick Access saves all the frequently used files and folders, so that users can access those files and folders easily the next time they want to use it.
By clicking Quick Access you can see, in the right pane, the folders and or files that you recently visited on Windows 10. It’s the equivalent of Favorites, found in older versions of Windows. It gives you access to your frequently used folders and allows you to open recent files as well. Quick Access can make your workflow faster and improve productivity. You may consider this a privacy concern, though, so there are a few things you can do to alleviate this concern. While there is an option to clear the menu, there may be times when you may want to keep most of the items and only remove those only one item.
How to remove a single item from the Recent Items menu
Open File Explorer and clicking Quick Access.
Right-click any file or folder you want to hide from Quick access and
choose “Remove from Quick Access” to hide the selected file or folder.
That’s all, Now the file or folder you selected will never show up in the Quick access again.
If you want to disable the Quick Access feature in order to give File Explorer a much cleaner look follow the article in the link below.