Remove Delete from panel (#322)

Now that we have context menu, we don't need it there

src/actions/actionDeleteSelected.tsx

@@ -1,4 +1,3 @@
-import React from "react";
 import { Action } from "./types";
 import { deleteSelectedElements } from "../scene";
 import { KEYS } from "../keys";
@@ -12,8 +11,5 @@ export const actionDeleteSelected: Action = {
   },
   contextItemLabel: "Delete",
   contextMenuOrder: 3,
-  keyTest: event => event.key === KEYS.BACKSPACE || event.key === KEYS.DELETE,
-  PanelComponent: ({ updateData }) => (
-    <button onClick={() => updateData(null)}>Delete selected</button>
-  )
+  keyTest: event => event.key === KEYS.BACKSPACE || event.key === KEYS.DELETE
 };