删除数据流
StreamWriter sr;
  string report;
  if (File.Exists(File_Name))
  {
  sr = File.AppendText(File_Name);
  report = "appended";
  }
  else
  {
  sr = File.CreateText(File_Name);
  report = "created";
  }
  sr.WriteLine(this.txtSendcontant.Text); 
  //怎么从数据流中删除这条
  sr.Close();


我在数据流里面找到了我要删的数据怎么删除掉？

------解决方案--------------------
C#追加文件
StreamWriter sw = File.AppendText(Server.MapPath(".")+"\myText.txt");
sw.WriteLine("追逐理想");
sw.WriteLine("kzlll");
sw.WriteLine(".NET笔记");
sw.Flush();
sw.Close();
C#拷贝文件
string OrignFile,NewFile;
OrignFile = Server.MapPath(".")+"\myText.txt";
NewFile = Server.MapPath(".")+"\myTextCopy.txt";
File.Copy(OrignFile,NewFile,true);

C#删除文件
string delFile = Server.MapPath(".")+"\myTextCopy.txt";
File.Delete(delFile);

C#移动文件
string OrignFile,NewFile;
OrignFile = Server.MapPath(".")+"\myText.txt";
NewFile = Server.MapPath(".")+"\myTextCopy.txt";
File.Move(OrignFile,NewFile);

C#创建目录
// 创建目录c:sixAge
DirectoryInfo d=Directory.CreateDirectory("c:\sixAge");
// d1指向c:sixAgesixAge1
DirectoryInfo d1=d.CreateSubdirectory("sixAge1");
// d2指向c:sixAgesixAge1sixAge1_1
DirectoryInfo d2=d1.CreateSubdirectory("sixAge1_1");
// 将当前目录设为c:sixAge
Directory.SetCurrentDirectory("c:\sixAge");
// 创建目录c:sixAgesixAge2
Directory.CreateDirectory("sixAge2");
// 创建目录c:sixAgesixAge2sixAge2_1
Directory.CreateDirectory("sixAge2\sixAge2_1");