Need picturebox to disappear after game over

I am making a PackMan game for my school project. After collecting all coins or running into a ghost or hitting a wall, it is game over, and a message box appears for retry or no. But the thing is, when I crash, the character keeps moving. How can I make so it just disappears or stands in one place? This is the code, which counts if all coins are collected or wall hit.

   public partial class Form1 : Form
{

    bool goup;
    bool godown;
    bool goleft;
    bool goright;

    int speed = 5;

    //1 and 2 ghost variables
    int ghost1 = 8;
    int ghost2 = 8;

    //ghost 3 variables
    int ghost3x = 8;
    int ghost3y = 8;

    //score
    int score = 0;
    public Form1()
    {
        Thread t = new Thread(new ThreadStart(SplashStart));
        t.Start();
        Thread.Sleep(5000);

        InitializeComponent();

        t.Abort();

    }

    public void SplashStart()
    {
        Application.Run(new splashscreen());
    }

    private void keyisdown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Left)
        {
            goleft = true;
            packman.Image = Properties.Resources.left;
        }

        if (e.KeyCode == Keys.Right)
        {
            goright = true;
            packman.Image = Properties.Resources.right;
        }

        if (e.KeyCode == Keys.Up)
        {
            goup = true;
            packman.Image = Properties.Resources.Up;
        }

        if (e.KeyCode == Keys.Down)
        {
            godown = true;
            packman.Image = Properties.Resources.down;
        }
    }

    private void keyisup(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Left)
        {
            goleft = false;
        }

        if (e.KeyCode == Keys.Right)
        {
            goright = false;
        }

        if (e.KeyCode == Keys.Up)
        {
            goup = false;
        }

        if (e.KeyCode == Keys.Down)
        {
            godown = false;
        }
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        label1.Text = "Score: " + score;

        //player movement
        if (goleft)
        {
            packman.Left -= speed;
            //moving player to the left
        }

        if (goright)
        {
            packman.Left += speed;
            //moving player to the right
        }

        if (goup)
        {
            packman.Top -= speed;
            //moving top
        }

        if (godown)
        {
            packman.Top += speed;
            //moving down
        }
        //end

        //moving ghost and bumping with the walls
        redGhost.Left += ghost1;
        yellowGhost.Left += ghost2;

        if (redGhost.Bounds.IntersectsWith(pictureBox1.Bounds))
        {
            ghost1 = -ghost1;
        }
        else if (redGhost.Bounds.IntersectsWith(pictureBox2.Bounds))
        {
            ghost1 = -ghost1;
        }

        if (yellowGhost.Bounds.IntersectsWith(pictureBox4.Bounds))
        {
            ghost2 = -ghost2;
        }
        else if (yellowGhost.Bounds.IntersectsWith(pictureBox3.Bounds))
        {
            ghost2 = -ghost2;
        }
        //end

        //check walls, ghosts and points

        foreach (Control x in this.Controls)
        {
            if (x is PictureBox && x.Tag == "coin")
                {
                    //score adds
                    if (((PictureBox)x).Bounds.IntersectsWith(packman.Bounds))
                    {
                        this.Controls.Remove(x); //removes that point
                        score++; // adds score
                    }
                }
            if (x is PictureBox && x.Tag == "wall" || x.Tag == "ghost")
            {
                if (((PictureBox)x).Bounds.IntersectsWith(packman.Bounds) || score == 30)
                {

                     //checks of ghost or player hits wall
                    packman.Left = 0;
                    packman.Top = 25;

                    DialogResult res = MessageBox.Show("Retry", "GAME OVER", MessageBoxButtons.YesNoCancel);
                    if (res == DialogResult.Yes)
                    {
                        Application.Restart();


                    }
                    else if (res == DialogResult.No)
                    {
                        Application.Exit();
                    }
                    else
                    {

                    }
                    timer1.Stop();
                }

            }

        }

        //end

        //ghost 3
        pinkGhost.Left += ghost3x;
        pinkGhost.Top += ghost3y;

        //ghost 3 bumping
        if (pinkGhost.Left < 1 || pinkGhost.Left+ pinkGhost.Width > ClientSize.Width -2 ||
           (pinkGhost.Bounds.IntersectsWith(pictureBox1.Bounds)) ||
            (pinkGhost.Bounds.IntersectsWith(pictureBox2.Bounds)) ||
            (pinkGhost.Bounds.IntersectsWith(pictureBox3.Bounds)) ||
            (pinkGhost.Bounds.IntersectsWith(pictureBox4.Bounds)))
        {
            ghost3x = -ghost3x;
        }

        if (pinkGhost.Top < 1 || pinkGhost.Top + pinkGhost.Height > ClientSize.Height - 2)
        {
            ghost3y = -ghost3y;
        }
        //end
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void Mainform_FormClosed(object sender, FormClosedEventArgs e)
    {

    }

    private void Form1_FormClosed(object sender, FormClosedEventArgs e)
    {
            //exit application when form is closed
            Application.Exit();
    }
}