JavaScript DOM remove element

I’m trying to test if a DOM element exists, and if it does exist delete it, and if it doesn’t exist create it.

var duskdawnkey = localStorage["duskdawnkey"];
var iframe = document.createElement("iframe");
var whereto = document.getElementById("debug");
var frameid = document.getElementById("injected_frame");
iframe.setAttribute("id", "injected_frame");
iframe.setAttribute("src", 'http://google.com');
iframe.setAttribute("width", "100%");
iframe.setAttribute("height", "400");

if (frameid) // check and see if iframe is already on page
{ //yes? Remove iframe
    iframe.removeChild(frameid.childNodes[0]);
} else // no? Inject iframe
{
    whereto.appendChild(iframe);
    // add the newly created element and it's content into the DOM
    my_div = document.getElementById("debug");
    document.body.insertBefore(iframe, my_div);
}

Checking if it exists works, creating the element works, but deleting the element doesn’t. Basically all this code does is inject an iframe into a webpage by clicking a button. What I would like to happen is if the iframe is already there to delete it. But for some reason I am failing.