It might be an easy question, but I can't seem to find the answer for it... I have this map service (Cities) that is currently not available, but I don't know how to remove it because it's not visible on the webmap. If I just click OK, the error message would come out every time I load the webapp. Is there a back-end way to remove the layer altogether? So, I don't need to rebuild another webmap without the unavailable layer?