How to add a WiX custom action that happens only on uninstall (via MSI)?

Question

I would like to modify an MSI installer (created through WiX) to delete an entire directory on uninstall.

I understand the RemoveFile and RemoveFo

Answer 1

There are multiple problems with yaluna's answer, also property names are case sensitive, Installed is the correct spelling (INSTALLED will not work). The table above should've been this:

Also assuming a full repair & uninstall the actual values of properties could be:

The WiX Expression Syntax documentation says:

In these expressions, you can use property names (remember that they are case sensitive).

The properties are documented at the Windows Installer Guide (e.g. Installed)

EDIT: Small correction to the first table; evidently "Uninstall" can also happen with just REMOVE being True.