I would like to disable the ability to make spatial/location edits to layers within the collector app, but still maintining the ability to edit fields within that layer.
This configuration is set within the service editor dialog when publishing the editable feature service. In the dialog, under the "Feature Access" settings (within the Capabilities section), you'll want to uncheck the option to "Allow geometry updates." This will allow the editor (be it in ArcGIS.com, desktop, or Collector) to update feature attributes but will prohibit them from updating the feature geometry.
I hope this helps.
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