Try to use EditItemTemplate with Item Template. like:
<Columns>
<asp:TemplateField HeaderText="Title">
<HeaderStyle Height="18px" HorizontalAlign="center"/>
<ItemStyle Width="20%" HorizontalAlign="center" />
<ItemTemplate>
<asp:Label ID ="lbl_title" runat ="server" text='<%#Bind("content_heading")%>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:Label ID ="lbl_title1" runat ="server" text='<%#Bind("content_heading")%>'></asp:Label>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Delete">
<HeaderStyle Height="18px" HorizontalAlign="center"/>
<ItemStyle Width="20%" HorizontalAlign="center" />
<ItemTemplate>
<asp:Button ID ="btn1" CommandArgument = '<%#Bind("page_id")%>' CommandName = '<%#Bind("div")%>' runat ="server" text ="Delete" />
</ItemTemplate>
</asp:TemplateField>
</Columns>