file.delete()

boolean b = file.delete();

public static void dateiVerschieben(File quellFile, File zielFile)
{
    try
    {
        boolean b = dateiKopieren(quellFile, zielFile);
            if(b)
            {
                b &= quellFile.delete();
            }            
    }
    catch(Exception x)
            {
                MessageVorlagen.ErrorMessage(x.toString(), null);
            }
}

public static boolean dateiKopieren(File source, File dest){
    try{
            java.io.FileInputStream sourceFile = new java.io.FileInputStream(source);

            try{
                    java.io.FileOutputStream destinationFile = null;

                    try{
                            destinationFile = new FileOutputStream(dest);
                            byte buffer[] = new byte[512 * 1024];
                            int reading;

                            while ((reading = sourceFile.read(buffer)) != -1){
                                    destinationFile.write(buffer, 0, reading);
                            }
                    } finally {
                            destinationFile.close();
                    }
            } finally {
                    sourceFile.close();
            }
    } catch (IOException e){
            e.printStackTrace();
            return false;
    }
    return true;
}