How to delete recent files and folders from File Explorer
To delete recent and frequently used files and folders from File Explorer:
- Start File Explorer.
- Click File> Change folder and search options.  Click on the "Delete" button in the "Privacy" section.
Applies to all versions of Windows 10
The File Explorer in Windows 10 tracks your recent and frequently used files and folders as part of its quick access feature. This screen allows you to quickly access your most used locations, so you do not need to navigate through the directory structures to find the file you opened yesterday.
While quick access is useful, sometimes you may want to delete it and start over. To do so, click on the File menu in the File Explorer and then on the "Change folder and search options" button.
The Folder Options pop-up menu will open. In the "Privacy" section, click on the "Delete" button to delete your quick access history. This will remove the indexes of your recent and frequently used files and folders, so they will start rebuilding from scratch as you use File Explorer.
It is worth noting that you can disable this behavior completely by using the two check boxes above "Delete" Button: the first deactivates the tracking of recently used files, while the second deletes the "Frequent folders" section .
Additional reading: File Explorer, Windows 10