SPList list = web.Lists[ListId];
SPListItemCollection splic = list.Items;
StringBuilder batchString = new StringBuilder();
batchString.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?><Batch>");

foreach (SPListItem item in splic)
{
        batchString.Append("<Method>");
        batchString.Append("<SetList Scope=\"Request\">" + Convert.ToString(item.ParentList.ID) + "</SetList>");
        batchString.Append("<SetVar Name=\"ID\">" + Convert.ToString(item.ID) + "</SetVar>");
        batchString.Append("<SetVar Name=\"Cmd\">Delete</SetVar>");
        batchString.Append("</Method>");
}

batchString.Append("</Batch>");
SPContext.Current.Web.ProcessBatchData(batchString.ToString());

SPList list = web.Lists[ListId];
SPListItemCollection splic = list.Items;
StringBuilder batchString = new StringBuilder();
batchString.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?><Batch>");

foreach (SPListItem item in splic)
{
        batchString.Append("<Method>");
        batchString.Append("<SetList Scope=\"Request\">" + Convert.ToString(item.ParentList.ID) + "</SetList>");
        batchString.Append("<SetVar Name=\"ID\">" + Convert.ToString(item.ID) + "</SetVar>");
        batchString.Append("<SetVar Name=\"Cmd\">Delete</SetVar>");
        batchString.Append("</Method>");
}

batchString.Append("</Batch>");
web.ProcessBatchData(batchString.ToString());

http://msftplayground.com/archive/2009/03/16/bulk-deletion-of-splistitems-splistitemcollection.aspx

This will delete all items in a SharePoint list. Better than looping through a SPListItemCollection and doing a .delete();

Delete all items in a SharePoint list

list, sharepoint

C#