how to edit and delete row in gridview asp.net

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C#

ASP.NET

I am using visual studio ultimate 2012. the problem is I can't delete a row in my project.

I am using following coding for load datas.

<form id="form1"  runat="server">
        
            Data Alternatif
            <div style="width: 100%; overflow: auto; margin-removed 20px; margin-removed 20px;">
            <asp:SqlDataSource ID="sdsKategori" runat="server" ConnectionString="<%$ ConnectionStrings:TopsisDbConnectionString %>" 
            SelectCommand="SELECT * FROM Alternatif">
            </asp:SqlDataSource>
            <asp:GridView ID="gvKategori" DataSourceID="SqlDataSource1" runat="server" AllowPaging="True" AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" AutoGenerateColumns="False" BorderStyle="Solid" BorderWidth="1px" PageSize="5">
                <AlternatingRowStyle/>
                <EditRowStyle/>
                <Columns>
                    <asp:CommandField HeaderText="Kelola Data" ShowSelectButton="true" ShowDeleteButton="true" ShowEditButton="true" ShowHeader="true" />
                    <asp:BoundField DataField="nm_alterntf" HeaderText="Nama Alternatif" SortExpression="nm_alterntf" />
                    <asp:BoundField DataField="kelulusan_air" HeaderText="Kelulusan Air Tanah" SortExpression="kelulusan_air" />
                    <asp:BoundField DataField="sist_aliran_air" HeaderText="Sistem Aliran Air" SortExpression="sist_aliran_air" />
                    <asp:BoundField DataField="manfaat_air" HeaderText="Pemanfaatan Air Tanah" SortExpression="manfaat_air" />
                    <asp:BoundField DataField="kemiringan" HeaderText="Kemiringan Tanah" SortExpression="kemiringan" />
                    <asp:BoundField DataField="jns_terbg" HeaderText="Jenis Penerbangan" SortExpression="jns_terbg" />
                    <asp:BoundField DataField="jrk_bandara" HeaderText="Jarak Lapangan terbang" SortExpression="jrk_bandara" />
                    <asp:BoundField DataField="bhy_banjir" HeaderText="Bahaya Banjir" SortExpression="bhy_banjir" />
                    <asp:BoundField DataField="inten_hjn" HeaderText="Intensitas Hujan" SortExpression="inten_hjn" />
                    <asp:BoundField DataField="utilitas" HeaderText="Utilitas" SortExpression="utilitas" />
                    <asp:BoundField DataField="lingk_bio" HeaderText="Lingkungan Biologis" SortExpression="lingk_bio" />
                    <asp:BoundField DataField="pertanian" HeaderText="Pertanian" SortExpression="pertanian" />
                    <asp:BoundField DataField="tnh_pntp" HeaderText="Tanah Penutup" SortExpression="tnh_pntp" />
                    <asp:BoundField DataField="kps_lhn" HeaderText="Kapasitas Lahan" SortExpression="kps_lhn" />
                    <asp:BoundField DataField="jln_msk" HeaderText="Jalan Masuk" SortExpression="jln_msk" />
                    <asp:BoundField DataField="bts_admin" HeaderText="Batas Administrasi" SortExpression="bts_admin" />
                    <asp:BoundField DataField="bis_bau" HeaderText="Kebisingan dan Bau" SortExpression="bis_bau" />
                    <asp:BoundField DataField="estetika" HeaderText="Estetika" SortExpression="estetika" />
                    <asp:BoundField DataField="biaya" HeaderText="Biaya" SortExpression="biaya" />
                </Columns>
                <EmptyDataRowStyle ForeColor="Red" />
                <HeaderStyle BackColor="#66FFFF"/>
                <PagerStyle />
                <RowStyle />
                <SelectedRowStyle />
                <SortedAscendingCellStyle/>
                <SortedAscendingHeaderStyle />
                <SortedDescendingCellStyle/>
                <SortedDescendingHeaderStyle/>
            </asp:GridView>
                <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:TopsisDbConnectionString %>" SelectCommand="SELECT * FROM [Alternatif]"></asp:SqlDataSource>
            </div>
            <br/>
    </form>