It's not showing up in 'add or remove programs' list. I can't see where to uninstall it from.

It depends on how you’ve installed the game. If you downloaded it directly from the browser, and the game didn’t come with an installer, then it’s unlikely there will be an entry in the “Add or remove programs list.” In those cases it often is enough to delete the files you extracted from the game download.

If you want an easier way to manage game installs we do have an app available here: https://itch.io/app

Just keep in mind the app can only manage games installed through the app. Any existing games you manually downloaded will not appear inside the app.