Do you need code to delete the files and folders from the selected folder? In that case, there is a technique I propose to you and that is based on recursion. That is, the ability of a function to call itself repeatedly until the task is complete; in this case, the function will call itself every time it detects a new folder/directory inside the designated original folder/directory.
Sooner or later your app will need to work with files, maybe to save the data generated with the app itself, to open the files created with other apps or because is the main purpose of the utility you are working on. Xojo gives you the class FolderItem fully loaded with a useful bunch of properties that allow you to examine the attributes of any file; for example, the creation or modification of dates, the file path (in several formats), if the file is an alias, etc. The FolderItem class also gives you the methods to do a lot of file operations without effort.