try this,
foreach (DataListItem anItem in DataList1.Items)
{
CheckBox chk = ((CheckBox)anItem.FindControl("deleteRec"));
if (chk != null)
{
if (chk.Checked)
{
TextBox tmpTxtBox = ((TextBox)anItem.FindControl("ImageID"));
string imageID = tmpTxtBox.Text;
proxy.DeleteRecord("delete * from Image where IMAGE_ID=" + imageID + "");
}
}
}