Remove the Readonly from field in sharepoint using custom code.

protected void Page_Load(object sender, EventArgs e)

        {

            try

            {

                string strSiteUrl = "http://wowdev:99/sites/testing";

                using (SPSite oSite = new SPSite(strSiteUrl))

                {

                    using (SPWeb oWeb = oSite.OpenWeb())

                    {

                        oWeb.AllowUnsafeUpdates = true;

                        SPList oList = oWeb.Lists["Tasks"];

                        SPField oField = oList.Fields.GetFieldByInternalName("Author");

                        oField.ReadOnlyField = false;

                        oField.Update(true);

                        oList.Update();

                    }

                }

            }

            catch (Exception ex)

            {

                ;

            }

        }