One of the benefits of working with the LabVIEW project is that you can organize your files logically without having to necessarily worry about moving them around on disk. This can also be a burden, however, when refactoring code... sometimes you remove a VI or typedef from your project, but it gets lost in the shuffle and remains on disk.
The attached tool makes it extremely easy to identify files on disk that are not in your project, and provides an easy mechanism to delete those files on disk if desired. To install the tool, simply copy the attached VI to your [LabVIEW 20xx]\project folder, then restart LabVIEW. You will now have a Tools > Find Non-Project Files... menu entry:
Selecting this menu entry will bring up the following dialog, which will display all files under the project folder on disk that do not reside anywhere in the project:
You can select one or more items in the list and click Delete Selected File(s) to move those files to the Recycle Bin. If there are items in the list that you need to keep, consider adding them to your project. To help with this, you can click the Explore button to open a Windows Explorer window with the selected file already highlighted.
The attached VI is saved in LabVIEW 2019, and is currently Windows-only (since it uses a .NET call to move files to the Recycle Bin instead of performing an unrecoverable Delete operation).
Thanks to LabVIEW community member Derek T. for providing me with the initial version of this tool.