Delete Button not working?

//Problem: User interaction doesn't provide desired results.
//Solution: Add interactivity so the user can manage daily tasks.

var taskInput = document.getElementById("new-task"); //new-task
var addButton = document.getElementsByTagName("button")[0]; //first button
var incompleteTaskHolder = document.getElementById("incomplete-tasks"); 
var completedTasksHolder = document.getElementById("completed-tasks"); 

//New Task List Item
var createNewTaskElement = function(taskString) {
  //Create List Item
  var listItem = document.createElement("li");

      //input(checkbox)
  var checkBox = document.createElement("input"); //checkbox
      //label
  var label = document.createElement("label");
      //input (text)
  var editInput = document.createElement("input"); //text
      //button.edit
  var editButton =document.createElement("button");
      //button.delete
  var deleteButton = document.createElement("button");
      //Each elements needs modifying
  checkBox.type = "checkbox";
  editInput.type = "text";

  editButton.innerHTML = "Edit";
  editButton.className = "edit";
  deleteButton.innerText="Delete";
  deleteButton.className = "delete";


  label.innerText = taskString
      //Each item needs appending
  listItem.appendChild(checkBox);
  listItem.appendChild(label);
  listItem.appendChild(editInput);
  listItem.appendChild(editButton); 
  listItem.appendChild(deleteButton); 

  return listItem;
}
//Add a new task
var addTask = function() {
  console.log("Add task...");
  //Create a new list item with the text from #new-task;
  var listItem = createNewTaskElement(taskInput.value);

  //Append List item ti incompleteTasksHolder
  incompleteTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
}

//Edit an existing task
var editTask = function(){
  console.log("Edit task...");

  var listItem = this.parentNode;

  var editInput = listItem.querySelector("input(type=text)");
  var label = listItem.querySelector("label");

  var containsClass = listItem.classList.contains("editMode");
  //if the class of the parent is .editMode
  if(containsClass){
    //Switch from .editMode
    //label text become the input's value
    label.innerText = editInput.value;
  } else {
    //Switch to .editMode
    //input value becomes the label's text
    editInput.value = label.innerText;
}
  //Toggle .editMode on the list item
  listItem.classList.toggle("editMode");
}
//Delete an existing task
var deleteTask = function(){
  console.log("Delete task...");
  var listItem = this.parentNode;
  var ul = listItem.parentNode;

  //Remove the parent list item from the ul 
  ul.removeChild(listItem); 
}
//Mark a task as complete
var taskCompleted = function() {
  console.log("Task complete...");
    //Apend the task list itme to the #completed-tasks
  var listItem = this.parentNode;
  completedTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskIncomplete);
}
//Mark a task as incomplete
var taskIncomplete = function () {
  console.log("Task incomplete...")
      //Append the task list item to the #incomplete-tasks
  var listItem = this.parentNode;
  incompleteTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
}

var bindTaskEvents = function(taskListItem, checkBoxEventHandler) {
  console.log("Bind list item events");
      //select listItems' children
  var checkBox = taskListItem.querySelector("input[type='checkbox']");
  var editButton = taskListItem.querySelector("button.edit");
  var deleteButton = taskListItem.querySelector("button.delete");


    //bind editTask to edit button
  editButton.onclick = editTask;
    //bind deleteTask to the delete button
  deleteButton.onclick = deleteTask;
    //bind checkBoxEventHandler to checkbox
  checkBox.onchange = checkBoxEventHandler;
}

//Set the click handler to the addTask function
addButton.onclick = addTask;

//cycle over incompleteTasksHolder ul list items
for(var i = 0; i < incompleteTaskHolder.children.length; i++){
    //bind events to list item's children (taskCompleted)
  bindTaskEvents(incompleteTaskHolder.children[i], taskCompleted);
}

//cycle over completedTasksHolder ul list items
for(var i = 0; i < completedTasksHolder.children.length; i++) {
bindTaskEvents(completedTasksHolder.children[i], taskIncomplete);
    //bind events to list item's children (taskIncomplete)
}