How is a radio button unchecked, if there's only one button?

I have these two radio buttons inside an Input Form:

<input type="radio" name="info_only_on" value="yes"> Info-only  
<input type="radio" name="info_only_on" value="off"> (Clear Button)

It creates two buttons, so the user can check info-only and then turn off info-only if they made a mistake. I created the 2nd button because once the radio button is checked, clicking it again, doesn't deselect it.

I've switched to type="checkbox", which does let the user deselect.

<input type="checkbox" name="info_only_on" value="yes">

Looking at specs for the radio type button, I'm not seeing anything for the user unchecking it. What am I missing?

I'm using html, php and avoiding javascript.