hello sir... i need to add a delete button to my code but i didn't know where can i put it.. i've tried but still not working.. please help me...this is the code..

package newproject1;

import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.*; import java.util.ArrayList; import java.util.Collections; import java.util.Scanner; import javax.swing.*;

public class DisplayInfo extends JFrame implements ActionListener {

private String fileName;
private Scanner input = null;
private Container container;
private JPanel panel1, panel2, panel3;
private JButton sortBut,delBut;
private FlowLayout panel1L, panel2L, panel3L;
private BorderLayout containerL;
private JTextArea ta1, taUN, taPWD, taAPP;
private JScrollPane pane;
private JMenuBar menuBar;
private JMenu menu;
private JMenuItem menuSort, menuBack;
private Font displayFont;

//constructor
public DisplayInfo ()
{       
    //set frame title
    setTitle("EASY ACCESS");

    //set size
    setSize(510,620);

    //set frame close operation
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //set frame to be visible
    setVisible(true);

    //Create Font
    displayFont = new Font("Serif", Font.BOLD, 14);

    //Create text field
    taUN = new JTextArea(1,13);     
    taPWD = new JTextArea (1,13);       
    taAPP = new JTextArea(1,13);    
    taUN.append("USERNAME");
    taPWD.append("PASSWORD");
    taAPP.append("APPICATION");


    //Create Button
    sortBut = new JButton ("Sort by UserName");
            delBut = new JButton ("Delete");

    //create text area
    ta1 = new JTextArea(30, 43);        

    //Create Panel
    panel1 = new JPanel();      
    panel2 = new JPanel();      
    panel3 = new JPanel();      

    //Create Layout
    panel1L = new FlowLayout();
    panel2L = new FlowLayout();
    panel3L = new FlowLayout ();
    containerL = new BorderLayout();

    //create JScrollPane
    pane = new JScrollPane(panel2);

    //Create menu bar
    menuBar = new JMenuBar();
    menuBar.setBackground(Color.cyan);

    //Create menu
    menu = new JMenu("File");

    //Create menu item
    menuSort = new JMenuItem("Sort By UserName");
    menuSort.setBackground(Color.CYAN);
    menuBack = new JMenuItem("Back to InsertData");
    menuBack.setBackground(Color.CYAN);

    //set editable false to all text areas
    ta1.setEditable(false);
    taUN.setEditable(false);
    taPWD.setEditable(false);
    taAPP.setEditable(false);


    //set background to text areas
    taUN.setBackground(Color.yellow);
    taPWD.setBackground(Color.BLUE);
    taAPP.setBackground(Color.green);


    //set Font for taUN, taPWD and taAPP

    taUN.setFont(displayFont);
    taPWD.setFont(displayFont);
    taAPP.setFont(displayFont);

    //set background to all panels
    panel1.setBackground(Color.cyan);
    panel2.setBackground(Color.cyan);
    panel3.setBackground(Color.cyan);

    //set Mnemonic for menu item
    menuSort.setMnemonic('S');
    menuBack.setMnemonic('B');

    //set Mnemonic for button
    sortBut.setMnemonic('S');
            delBut.setMnemonic('D');

    //set Accelerator for menu item
    menuSort.setAccelerator(KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_S, java.awt.Event.CTRL_MASK));
    menuBack.setAccelerator(KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_B, java.awt.Event.CTRL_MASK));

    //set top and bottom layout
    panel1.setLayout(panel1L);
    panel2.setLayout(panel2L);
    panel3.setLayout(panel3L);

    //get all component
    container = getContentPane();

    //set container layout
    container.setLayout(containerL);    

    //Add label and text field onto panel 2
    panel1.add(taUN);
    panel1.add(taPWD);
    panel1.add(taAPP);


    //Add text field onto panel 2
    panel2.add(ta1);        

    //Add text field onto panel 3
    panel3.add(sortBut);
            panel3.add(delBut);

    //Add menu items to menu
    menu.add(menuSort);
    menu.add(menuBack);

    //Add menu to menu bar
    menuBar.add(menu);

    //Add menu bar to JFrame
    setJMenuBar(menuBar);

    //Add listener to all menu items
    menuSort.addActionListener(this);
    menuBack.addActionListener(this);

    //add listener button
    sortBut.addActionListener(this);

    //add panel onto container
    container.add(pane,BorderLayout.CENTER);
    container.add(panel3,BorderLayout.SOUTH);
    container.add(panel1,BorderLayout.NORTH);

    try
    {
        fileName = "User.dat";
        input = new Scanner(new FileInputStream(fileName));

        while(input.hasNext())
        {
            ta1.append(input.nextLine() + "\n");
        }
        input.close();
    }
    catch(FileNotFoundException fnfe)
    {
        System.err.println("Couldn't Find " + fileName + " !!");

    }

    {
        System.err.println("An Error has been occured!! ");
    }
}


@Override
public void actionPerformed(ActionEvent ae)
{
    if(ae.getSource() == sortBut)
    {
        try
        {               
            ArrayList<String> rows = new ArrayList<>();
            FileWriter writer;
            try (BufferedReader reader = new BufferedReader(new FileReader("User.dat"))) {
                String s;
                while((s = reader.readLine())!=null)
                    rows.add(s);
                Collections.sort(rows);
                writer = new FileWriter("User.dat");
                for(String cur: rows)
                    writer.write(cur+"\n");
            }
            writer.close();

            fileName = "User.dat";
            input = new Scanner(new FileInputStream(fileName));

            ta1.setText(null);
            while(input.hasNext())
            {                   
                ta1.append(input.nextLine() + "\n");
            }
            input.close();
        }
        catch(Exception e)
        {
        }
    }

    String menuCommand = ae.getActionCommand();

    //Event handler for menu item
    if(ae.getSource() instanceof JMenuItem){
        switch (menuCommand) {
            case "Sort By UserName":
                try
                {               
                        ArrayList<String> rows = new ArrayList<>();
            FileWriter writer;
            try (BufferedReader reader = new BufferedReader(new FileReader("User.dat"))) {
                String s;
                while((s = reader.readLine())!=null)
                    rows.add(s);
                Collections.sort(rows);
                writer = new FileWriter("Usert.dat");
                for(String cur: rows)
                    writer.write(cur+"\n");
            }
                    writer.close();

                    fileName = "User.dat";
                input = new Scanner(new FileInputStream(fileName));

                ta1.setText(null);
                while(input.hasNext())
                {                   
                        ta1.append(input.nextLine() + "\n");
                }
                input.close();
                }
                catch(Exception e)
                {
                }

                break;



            case "Back to InsertData":
                //calling the method openInsertData
                openInsertData();
                //set the DisplayInfo to not appear when InsertData is opened
                setVisible(false);
                break;
        }
    }
}   

public void openInsertData()
{
    //open InsertData
    new InsertData();

}

}