Set Date format for TextBox from Database using C# in ASP.Net

hello , 

When i try search data from sql and get all data in textbox the DATE show full date and time

i want only date like 2021/01/23

my html : 

<asp:TextBox ID="txtBoxDate8" runat="server" AutoPostBack="True" Font-Bold="True" Font-Names="Arial" Font-Size="X-Large" Style="text-align: center" ForeColor="Blue" BackColor="#FFFFCC" BorderColor="#FFFFCC"></asp:TextBox>
<asp:TextBox ID="txtBoxDate10" runat="server" AutoPostBack="True" Font-Bold="True" Font-Names="Arial" Font-Size="X-Large" ForeColor="Red" Style="text-align: center" BackColor="#FFFFCC" BorderColor="#FFFFCC"></asp:TextBox>

C#: 

        protected void Searchdata()
        {
            try
            {
                String constring = ConfigurationManager.ConnectionStrings["kankonConnectionString"].ConnectionString;

                SqlConnection sqlcon = new SqlConnection(constring);
                String pname = "Insert_Userupdate"; ;

                sqlcon.Open();
                SqlCommand com = new SqlCommand(pname, sqlcon);

                com.CommandType = CommandType.StoredProcedure;

                com.Parameters.AddWithValue("civilid", txtSearch.Text);
                com.Parameters.AddWithValue("name", txtSearch.Text);

                SqlDataReader rdr;
                rdr = com.ExecuteReader();
                if (rdr.Read())
                {
                    txtUsername.Text = rdr["name"].ToString();

                    joptitel.Text = rdr["jop"].ToString();
                    markazel3mel.Text = rdr["markazel3mal"].ToString();

                    filenumber.Text = rdr["fileid"].ToString();
                    civilid.Text = rdr["civilid"].ToString();
                    eldarajah.Text = rdr["eldarajah"].ToString();

                    workdate.Text = rdr["workdate"].ToString();

                    txtBoxDate8.Text = rdr["DateTimePicker1"].ToString();
                    txtBoxDate10.Text = rdr["DateTimePicker2"].ToString();

                    string dtVal = workdate.Text.Trim();
                    DateTime Dob = Convert.ToDateTime(dtVal);
                    Label_day.Text = CalculateAge(Dob);
                }
                else
                {
                    ClientScript.RegisterClientScriptBlock(GetType(), "alert", "alert('" + "لاتوجد بيانات\\n " + txtSearch.Text.ToString() + "');", true);
                }

                sqlcon.Close();
            }
            catch (Exception)
            {
            }
        }

SQL :

[DateTimePicker1] [date] NULL,
[DateTimePicker2] [date] NULL,

USE [kankon]
GO
/****** Object:  StoredProcedure [dbo].[Insert_Userupdate]    Script Date: 1/23/2021 2:47:42 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER procedure [dbo].[Insert_Userupdate]
(
    @name nvarchar(max),
    @civilid nvarchar(max)
)
as
begin
    Select * from Table_infoname where name LIKE '%' + @name +'%' OR civilid LIKE '%' + @civilid +'%'
end