For this, use XLS Padlock's own Deactivation feature rather than trying to delete the activation entries from the registry by hand. Deactivation is the supported way to remove an activation from a machine: it clears the local activation cleanly so you can re-run the trial and activation flow from a fresh state, which is exactly what you need between test cycles, and it does the right thing wherever the data physically sits.
I would steer away from wiping XLS Padlock's internal activation entries directly from your uninstaller. They are stored in a form tied to your application, deleting the wrong branch could affect other protected apps on the same machine, and the internal layout can change between versions, so a hard-coded "Remove a Registry Key" action is fragile. Deactivation is version-safe and is the intended mechanism for precisely this.
If your real goal is a fully clean test machine between runs, deactivating the app, or testing under a fresh Windows user account or a VM snapshot, gets you there reliably without touching the registry manually.