How do I delete a file using the "Add File Removal"?

How do I delete a file using the "Add File Removal"?

In InstallShield->Application Data->Files and Folders->I go to the parent directory.

Then I right click in "Destination computer's Files and select "Add File Removal".

If I select the "Remove files from the folder" radio button, how do I delete a specific sub-directory (i.e. \DirectoryToRemove, instead of a file?

The folder described by the radio buttons is the one listed after Location (the blacked out part of your screen capture). You can either remove files from the location in question, or the folder itself. If you want to remove a child of that folder, you will have to add a file removal to that folder, perhaps adding the folder first.

This is built upon the RemoveFile table, which is the source of the requirement that a folder be empty if you want to remove it. However if you go directly to the table, you can avoid creating a directory entry for a subdirectory by referencing a Property instead of a Directory. (If you go that route, note you will then have to ensure the referenced property has the correct value.)