> making it impossible to kill the ad layer

Use the context menu. There is an option to "hide" (delete) the ad there.

Another option is this bookmarklet (only works if the element that should be deleted isn't in an iframe):

    javascript:(function(){var e=document.body.style.cursor;document.body.style.cursor="crosshair";var t=document.createElement("div");var n="border:1px solid #3280FF;background-color:rgba(50,128,255,0.5);position:absolute;z-index:2147483647;display:none;";var r="pointer-events:none;";var i="transition:width 60ms,height 60ms,left 60ms,top 60ms;";n+=r+"-webkit-"+r+"-moz-"+r;n+=i+"-webkit-"+i+"-moz-"+i;t.setAttribute("style",n);document.body.appendChild(t);var s=null;var o=function(e){var n=e.target;if(n!==s&&n.parentNode){var r=n.getBoundingClientRect();var i=document.documentElement;var o=document.body;var u=i.clientTop||o.clientTop||0;var a=i.clientLeft||o.clientLeft||0;var f=window.pageYOffset||i.scrollTop||o.scrollTop;var l=window.pageXOffset||i.scrollLeft||o.scrollLeft;var c=l-a+r.left-1;var h=f-u+r.top-1;t.style.display="block";t.style.left=c+"px";t.style.top=h+"px";t.style.width=r.width+"px";t.style.height=r.height+"px";s=n}};var u=function(n){document.body.style.cursor=e;if(n.target.parentNode)n.target.parentNode.removeChild(n.target);if(t.parentNode)t.parentNode.removeChild(t);window.removeEventListener("click",u,false);window.removeEventListener("mouseover",o,false);n.stopPropagation();n.preventDefault()};window.addEventListener("mouseover",o,false);window.addEventListener("click",u,false)})();void(0)