I have a webmap (link) which was using a layer, published to AGOL, which is no longer available. The layer, County Boundaries, wasn't part of my uploaded content. I get an error message that the layer failed to load but I don't see any way to remove the layer from my map and replace it. It no longer shows up as a layer in the map.
What am I missing? How do I remove this so I can replace it?