To delete an existing folder you need to execute a DELETE request against the
/libraries/:libraryId/folders/:folderId endpoint.
The folderId uniquely identifies the folder and the libraryId uniquely identifies the library inside which the folder is located.
This is a destructive operation which cannot be undone! If the deleted folder is in-use -> all opened files from it will be closed and users will lose access to the folder. All files and subfolders nested in the folder will be permanently deleted.