How to hide a column in the edit form in sharepoint

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;
namespace HideinEditForm
{
class Program
{
static void Main(string[] args)
{
using (SPSite site = new SPSite("http://serverName:1111/"))
{
using (SPWeb web = site.RootWeb)
{
SPList list = web.Lists.TryGetList("cl");
SPField field = list.Fields["TestCol"];
field.ShowInEditForm = false;
field.Update();
}
}
}
}
}