implement destroy util function in js utility registry

static/js/services/utilRegistry.js

@@ -106,8 +106,25 @@
     }
 
     function _destroyUtilInstances(name) {
-      console.log('TODO: destroy util instances', { name });
+      activeUtilInstances
-      // call destroy on each activeUtilInstance that matches the name
+        .map(function(util, index) {
+          return {
+            util: util,
+            index: index,
+          };
+        }).filter(function(activeUtil) {
+          // find utils instances to destroy
+          return activeUtil.util.name === name;
+        }).forEach(function(activeUtil) {
+          // destroy util instance
+          activeUtil.util.destroy();
+          delete activeUtilInstances[activeUtil.index];
+        });
+
+      // get rid of now empty array slots
+      activeUtilInstances = activeUtilInstances.filter(function(util) {
+        return !!util;
+      })
     }
 
     // public API