The application doesn't have a very strong encryption, therefore the only good thing to do is to actually remove the software and then install it again. The uninstall procedure will remove the password, then after a new installation, the software can be configured again with a new one and that's it.
If you need the installation package, kindly visit the following website: http://pc-auto-shutdown.software.informer.com/download/
- Download instructions: click download and wait a few seconds and a pop up will appear automatically.