The article mentioned above is not complete. There is no uninstall program in the Prey folder on my Win64 machine. When I perform the steps indicated and re-install with the MSI, there is still no uninstall program in the Prey folder to run. The application also (obviously) does not appear in the Programs and Features control panel either.
The instructions listed on that page incorrectly state:
you'll need to run the MSI installer again. Just grab the latest MSI package for Prey, run, and then follow the instructions.
The issue is that you MUST download the EXE installer and NOT the MSI. The MSI installer does not put the uninstall.exe in the Prey folder while the other does.