In some situations, you may have a web map with a bad feature service you are trying to edit or remove, but it has seemed to have disappeared, or you can no longer access the feature service in question.
Solution
When you open the web map that has the bad feature service, ESRI recommends that you simply save the web map.
Since the bad layer is not loading or showing up in the web map, when you save it, it will no longer try to connect to the feature service in question.
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