How to remove a line from a file?

Qt Code: 
  1. void DeslocaPt::skip(QStringList &l, QStringList &p)
  2. {
  3.     QString arqAlt = altEdit->text();
  4.     QString line, linesimp;
  5.     QFile file(arqAlt);
  6.     if(file.open(QIODevice::ReadWrite | QIODevice::Text)){
  7.         QTextStream out(&file);
  8.         while(!out.atEnd()){
  9.             line = out.readLine();
  10.             linesimp = line.simplified();
  11.             for (int i = 0; i < l.size(); ++i)
  12.                 if (linesimp.contains(QString("S%1 %2").arg(l.at(i)).arg(p.at(i)))){
  13.                     line.clear();
  14.                 }
  15.  
  16.             out << line << endl;
  17.         }
  18.     }
  19.     file.close();
  20. }
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I tried to do:
Qt Code: 
  1. line.clear();
  2. out << line << endl;
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I used this command to position
Qt Code: 
  1. out.seek(out.pos() - line.size() );
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result is not satisfactory. Any idea?