diff --git a/ed/css/av1-avif.json b/ed/css/av1-avif.json
deleted file mode 100644
index 2096e628290e..000000000000
--- a/ed/css/av1-avif.json
+++ /dev/null
@@ -1,21 +0,0 @@
-{
-  "spec": {
-    "title": "AV1 Image File Format (AVIF)",
-    "url": "https://aomediacodec.github.io/av1-avif/"
-  },
-  "properties": [],
-  "atrules": [],
-  "selectors": [],
-  "values": [],
-  "warnings": [
-    {
-      "msg": "Dangling value",
-      "name": "sato",
-      "prose": "When a derived image item is of type sato, it is called a Sample Transform Derived Image Item, and its reconstructed image is formed from a set of input image items, constants and operators.",
-      "href": "https://aomediacodec.github.io/av1-avif/#valdef-sample-transform-derived-image-item-type-sato",
-      "type": "value",
-      "value": "sato",
-      "for": "Sample Transform Derived Image Item Type"
-    }
-  ]
-}