Basic question on Gridview and delete button disappear on postback

Good day,
I have a gridview setup and I added a button Delete in the gridview so I can delete rows as I want from the Itemslist. Basicaly I have a drop down and I choose the items I want to add into the gridview and click the Add Item button. On page load the button is there but as soon as I add an items to the gridview the delete button disappear. It's probably something that I am over looking or something I'm also kind of a noob in .net.
aspx code:
<asp:GridView ID="ItemsViews" runat="server" GridLines="Horizontal" style="text-align: center" Width="912px" AutoGenerateColumns="False"> <Columns> <asp:CommandField ShowD ...