Remove unused types

Summary: Little cleanup

Reviewed By: nikoant

Differential Revision: D22374892

fbshipit-source-id: 4d561992b36bff212b926c2e52b73c6287851523

desktop/plugins/seamammals/src/index.tsx

@@ -41,10 +41,6 @@ function renderSidebar(row: Row) {
   );
 }
 
-type State = {
-  selectedID: string | null;
-};
-
 type PersistedState = {
   [key: string]: Row;
 };