I created a form where i can add a task, Display the saved records. I want to delete any task which is not needed. So I provided  delete button in the list of tasks. I am trying to delete the task with Event handlers.

Parent Component:
<aura:component controller="taskController">
    <aura:attribute type="task__c" name="task" default="{'sobjectType':'task__c',
                                                        'Name':'',
                                                        'Due_Date__c':''}" />
    <aura:attribute type="task__c[]" name="tasks" />
    <form>
        <div class="slds-form-element">
            <label class="slds-form-element_label">Task Name</label>
            <div class="slds-form-element_control">
                <ui:inputText aura:id="taskName" class="slds-input slds-size--1-of-3" value="{!v.task.Name}" />
            </div>
        </div>
        <div class="slds-form-element">
            <label class="slds-form-element_label">priority value</label>
            <div class="slds-form-element_control">
                <ui:inputSelect aura:id="taskPriority" class="slds-input slds-size--1-of-3" value="{!v.task.Priority__c}">
                    <ui:inputSelectOption label="1" text="1" />
                    <ui:inputSelectOption label="2" text="2" />
                    <ui:inputSelectOption label="3" text="3" />
                    <ui:inputSelectOption label="4" text="4" />
                    <ui:inputSelectOption label="5" text="5" />
                </ui:inputSelect>
            </div>
        </div>
        <div class="slds-form-element">
            <label class="slds-form-element_label">Due Date</label>
            <div class="slds-form-element_control">
                <ui:inputDate aura:id="taskDate" displayDatePicker="true" class="slds-input slds-size--1-of-3" value="{!v.task.Due_Date__c}" />
            </div>
        </div>
        <div class="slds-form-element">
            <ui:Button label="Create Task" class="slds-button slds-button--success" press="{!c.insertTask}" />
        </div>
    </form>
    <ui:Button label="View Today's Task" class="slds-button slds-button--success" press="{!c.displayTasks}" />
    <ui:Button label="View Daily Task" class="slds-button slds-button--success" press="{!c.displayGroupedTasks}" />
    <div id="errorMessage"></div>
    <aura:iteration items="{!v.tasks}" var="task1">
        <c:taskListItem task2="{!task1}"/>
    </aura:iteration>
</aura:component>

taskFormController:
({
   
    insertTask : function(component, event, helper) {
        if(helper.validateTask(component)){
            helper.createTask(component);
         }
    },
    displayTasks : function(component, event, helper){  
        helper.loadRequiredTask(component); 
    },
    displayGroupedTasks : function(component, event, helper){
        helper.loadGroupedTasks(component);
    }

})

taskFormHelper:
({
    validateTask: function(component) {
        var validTask = true;
        var taskName = component.find("taskName");
        var taskNameValue = taskName.get("v.value");
        if ($A.util.isEmpty(taskNameValue)) {
            alert("Name failure" + taskNameValue);
            validTask = false;
        }
       var taskPriority = component.find("taskPriority");
        var taskPriorityValue = taskPriority.get("v.value");
        if ($A.util.isEmpty(taskPriorityValue)) {
            validTask = false;
                console.log("value failure" + taskPriorityValue);
        } 
        return validTask;
    },
    createTask: function(component) {
        var action = component.get("c.saveTask");
        var task =component.get('v.task');
        action.setParams({
            "task": task
        });
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (component.isValid() && state === "SUCCESS") {
                console.log("Successfully Inserted");
                component.set("v.tasks",response.getReturnValue());
            }
        })
        $A.enqueueAction(action);
    },
    loadRequiredTask: function(component){
        var action = component.get("c.loadTasks");
        action.setCallback(this,function(response){
            var state = response.getState();
            if(component.isValid()&& state=='SUCCESS'){
                console.log(typeof(response.getReturnValue()));
                if(response.getReturnValue().length>0)
                    component.set("v.tasks", response.getReturnValue());
                else{
                    console.log("In empty");
                   document.getElementById("errorMessage").innerHTML='<p>"There are no Tasks pending for Today"</p>'; 
            }
            }
        })
        $A.enqueueAction(action);
    },
    
    loadGroupedTasks: function(component) {
        var action = component.get("c.loadGroupedTasks");
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (component.isValid() && state === "SUCCESS") {
                console.log("Successfully Retrieved");
                component.set("v.tasks",response.getReturnValue());
            }
        })
        $A.enqueueAction(action);
    }
    
})

taskListItem.cmp:
<aura:component controller="taskListController">
    <aura:attribute type="task__c" name="task2" />
    <aura:registerEvent name="deleteTask" type="c:TaskDeleteEvent" />
    <aura:handler name="TaskDeleteEvent" event="c:TaskDeleteEvent" action="{!c.deleteTask}"/>
    <p>
        Task Name:
        <ui:outputText value="{!v.task2.Name}" />
    </p>
    <br></br>
    <p>
        Priority Value:
        <ui:outputText value="{!v.task2.Priority__c}" />
    </p>

    <br></br>
    <p>
        Due Date:
        <ui:outputDate value="{!v.task2.Due_Date__c}" />
    </p>
    <br></br>
    <p>
        <ui:Button class="slds-button" label="Delete" press="{!c.deleteTask}" /> 
    </p>
    -------------------------------------------------------------------------------------------------

</aura:component>

taskListItemController.js:

({
    deleteTask : function(component, event, helper) {
        var deleteTask = component.get("v.task2");
        var TaskDeleteEvent = component.getEvent("deleteTask");
        TaskDeleteEvent.setParams({"task2":deleteTask}).fire();
    }
})

taskListController.apxc:

public class taskListController {
 @AuraEnabled
    public static void deleteTask(sobject task){
        delete task;
       }
}

TaskDeleteEvent.evt:

<aura:event type="COMPONENT" description="Event template" >
    <aura:attribute name="task2" type="task__c" />
</aura:event>



Delete is not working.