How to get specific value from datalist

how do i get only specific value on a datalist i want to delete images i display on the datalist but i only want to delete a spefic image i have a label with the image id so i want to use the id as my peremeter
 
here is my code
 

<asp:DataList ID="DataList2" runat="server" DataKeyField="pid"
        DataSourceID="SqlDataSource2" RepeatColumns="3"
            onselectedindexchanged="DataList2_SelectedIndexChanged">
        <ItemTemplate>
            <asp:Label ID="pidLabel" runat="server" Text='<%# Eval("pid") %>' />
            <br />
            <asp:Image ID="Image1" runat="server"
                ImageUrl='<%# Eval("picurl","~/images/{0}") %>' BorderColor="Red"
                BorderStyle="Groove" Height="200px" Width="200px" /><br />
            uploadedby:
            <asp:Label ID="uploadedbyLabel" runat="server"
                Text='<%# Eval("uploadedby") %>' />
            <br />
            <br />
            <asp:Button ID="Button3" runat="server" Text="Delete"  OnClick = "btnPhotos_Click"/>
 
        </ItemTemplate>
    </asp:DataList>