How do I close the game from a botton in game?

I'm doing a small lite widget in construct to be used on a site. After running the small little mini game, I want to have a close button in the game that closes the game. (or the div/iframe where the game is running)

How do I go about doing that?

And some follow up questions:

Should the game be running in an iframe on the same site? or is it possible to run the game in a div, with the canvas object directly?

Thanks

No that will close the browser window. I just want to close the div/iframe where the game is running.

To clarify. On the site there is a button to start the game:

Clicking this button will open a modal/div with an iframe with the game running inside.

Once you've finished play the game, there is a close button in the game.

I need to click this ingame button to close the modal/div on the site.