Bind data to datagridview without using database

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C#

VS2010

SharePoint2010

hello ,
1)I have 3 dropdown list and 1 datagridview and when we select the data in dropdown list and click add button, the data will add into data grid view.
2)Now my problem is I only can add data into data grid view.So , how to modify this code to add delete and reset button to delete slected row in datagrid view.
thank you for help.:)

 protected void BindGrid(int rowcount)
        {

            DataTable dt = new DataTable();
            DataRow dr;
            dt.Columns.Add(new System.Data.DataColumn("Document No",
typeof(String)));          
            dt.Columns.Add(new System.Data.DataColumn("Document Title", typeof(String)));
            dt.Columns.Add(new System.Data.DataColumn("Revision", typeof(String)));
            dt.Columns.Add(new System.Data.DataColumn("File", typeof(String)));

            if (ViewState["CurrentData"] != null)
            {

                for (int i = 0; i < rowcount + 1; i++)
                {

                    dt = (DataTable)ViewState["CurrentData"];

                    if (dt.Rows.Count > 0)
                    {

                        dr = dt.NewRow();

                        dr[0] = dt.Rows[0][0].ToString();
                    }

                }

                dr = dt.NewRow();
                dr[0] = DropDownList19.Text;            
                dr[1] = DropDownList21.Text;
                dr[2] = DropDownList20.Text;
                dt.Rows.Add(dr);
            }

            else
            {

                dr = dt.NewRow();
                dr[0] = DropDownList19.Text;
                dr[1] = DropDownList21.Text;
                dr[2] = DropDownList20.Text;
                dt.Rows.Add(dr);
            }
            // If ViewState has a data then use the value as the DataSource

            if (ViewState["CurrentData"] != null)
            {

                GridView1.DataSource = (DataTable)ViewState["CurrentData"];

                GridView1.DataBind();

            }

            else
            {

                // Bind GridView with the initial data assocaited in the DataTable

                GridView1.DataSource = dt;

                GridView1.DataBind();
            }

            // Store the DataTable in ViewState to retain the values

            ViewState["CurrentData"] = dt;
        }
//////////////////////////add button//////////////////////////////////

        protected void Button1_Click(object sender, EventArgs e)
        {
            // Check if the ViewState has a data assoiciated within it. If 

            if (ViewState["CurrentData"] != null)
            {

                DataTable dt = (DataTable)ViewState["CurrentData"];

                int count = dt.Rows.Count;

                BindGrid(count);

            }

            else
            {

                BindGrid(1);
            }

            DropDownList4.Text = string.Empty;
            DropDownList4.Focus();
            {

                string uploadedFilePath = @"C:\";
                string sharePointListPath = "http://path/";

                if (FileUpload1.HasFile)
                    try
                    {
                        FileUpload1.SaveAs(
                            uploadedFilePath + FileUpload1.FileName);

                        errorlabaelupload.Text = "File name: " +
                             FileUpload1.PostedFile.FileName + "<br>" +
                             FileUpload1.PostedFile.ContentLength + " bytes<br>" +
                             "Content type: " +
                             FileUpload1.PostedFile.ContentType;

                        UploadFileToSharePoint(
                            uploadedFilePath + FileUpload1.FileName,
                            sharePointListPath + FileUpload1.FileName);
                    }
                    catch (Exception ex)
                    {
                        errorlabaelupload.Text = "ERROR: " + ex.Message.ToString();
                    }
                else
                {
                    errorlabaelupload.Text = "You have not specified a file.";
                }
            }


        }

    }
}