列表项对象删除（添加列表根据标题判断如果存在就删除）

 SPListItemCollection listItems = web.Lists[docLibName].Items;
            int itemCount = listItems.Count;
            for (int k = 0; k < itemCount; k++)
            {
                SPListItem item = listItems[k];

                if (li["标题"].ToString() == item["标题"].ToString())
                {
                    listItems.Delete(k);
                }
            }

方法二

       SPListItemCollection listItems = web.Lists[docLibName].Items;
            foreach (SPListItem list in listItems)
            {
                if (li["标题"].ToString() == it["标题"].ToString())
                {
                    list.Delete();
                }
            }