Use delete keyword

voicegardens/static/voicegardens.js

@@ -1,4 +1,5 @@
-"use strict";
+// Note(decentral1se): in order to use the `delete` operator
+// "use strict";
 
 //
 // Voicegardens front-end Javascript
@@ -92,7 +93,7 @@ function gardenOfflineLimits() {
   for (let i = 0; i < shapes.length; i++) {
     let shape = shapes[i];
     shape.hide();
-    shape = null;
+    delete shape;
   }
 
   shapes = [];