HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

I can't uninstall the game (unins000.exe); it displays the message: "
"This program can only be installed in a 64-bit Windows environment."
What should I do?

CCleaner doesn't detect the game, and Your Uninstaller! doesn't either.

Added 1 hour 20 minutes ago
Hello?!