Thank you Christoph!  That does it.  I didn't know there was a System Administrator option.  I would mark it as the answer but I don't have enough points to do so.

Hi,

To remove a project folder from Odoo's Documents app after deleting the project, first ensure you have administrator rights. Navigate to the Documents app, locate the project folder, and switch to list view for easier selection. Look for an "Action" menu or a direct "Delete" button after selecting the folder. Confirm the deletion to permanently remove the folder and its contents.

If the deletion fails, ensure the folder is empty of documents and subfolders, and try deleting those first. Check for an "Archive" option instead of "Delete," and if present, unarchive the folder before attempting deletion. If issues persist, activate developer mode for more options. In rare cases with custom modules, database constraints might prevent deletion, requiring assistance from an Odoo developer. Remember that deletion is usually permanent, so ensure you have a backup if needed, and be aware of potential impacts on other modules relying on those documents.

Hope it helps