remove "unpin" button when unpinning succeeded

src/index.js

@@ -23,7 +23,8 @@ async function initialize() {
         const unpin_button = document.createElement('button');
         unpin_button.innerText = 'unpin';
         unpin_button.onclick = async function() {
-            console.log('unpinned', await node.pin.rm(cid));
+            await node.pin.rm(cid);
+            unpin_button.remove();
         };
         item.appendChild(unpin_button);
         pin_list.appendChild(item);