remove gulf poly and data

site-data/margin/gulf-coast.geojson

-{
-  "type": "Feature",
-  "geometry": {
-    "type": "Polygon",
-    "coordinates": [[
-      [-100.50, 24.50],
-      [-85.00, 24.50],
-      [-81.50, 24.25],
-      [-74.00, 24.25],
-      [-72.00, 32.50],
-      [-69.00, 42.00],
-      [-70.50, 42.50],
-      [-74.00, 41.50],
-      [-78.00, 39.00],
-      [-78.50, 36.50],
-      [-85.00, 33.00],
-      [-87.50, 34.50],
-      [-88.00, 37.50],
-      [-90.50, 37.50],
-      [-94.00, 34.50],
-      [-98.00, 34.50],
-      [-101.00, 32.00],
-      [-100.50, 24.50]
-    ]]
-  },
-  "properties": {
-    "name": "Gulf Coast Sediment Depth",
-    "id": "gulf-coast",
-    "model": "CPADepthNSHM",
-    "spacing": 0.05
-  }
-}