Please how do I unload and hide an external image?

I have been trying for a few hours now just to unload an image but I get an error when I try it which sais ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.
at flash.display:isplayObjectContainer/removeChild()
at tester_fla::MainTimeline/ontester2ButtonClick()

I have 2 buttons on the stage the first one adds the image and is called tester_btn, the second (attempts) to unload and hide the image and is called tester2_btn

My code is as follows:

tester_btn.addEventListener(MouseEvent.CLICK,ontes terButtonClick);
function ontesterButtonClick(event:MouseEvent):void {

var myrequest:URLRequest=new URLRequest (“HomeLogo.png”);
var myloader:Loader = new Loader();
myloader.load(myrequest);
myloader.contentLoaderInfo.addEventListener(Event. COMPLETE, imgLoaded);
function imgLoaded(event:Event):void{
addChild(myloader);
}
}

tester2_btn.addEventListener(MouseEvent.CLICK,onte ster2ButtonClick);
function ontester2ButtonClick(event:MouseEvent):void {
var myrequest:URLRequest=new URLRequest (“HomeLogo.png”);
var myloader:Loader = new Loader();
myloader.unload();
stage.removeChild(myloader);

}

Any help will be much appreciated!