$login = "ляляля";
    $file_array = file("./iki.txt");
        if($file_array)
        {
          if ($file = fopen("./iki.txt","wt"))
            {
                $laststroka=count($file_array);
                 
                 for($i=0; $i < $laststroka; $i++)
                {
                $tekstr=trim($file_array[$i]);
                 if ($tekstr <> $login) 
                 {
                      fwrite($file, $tekstr."\n");
                 } 

                } 
                fclose($file);
                print("1");

$word = 'lalala';
$file = file_get_contents('./file.txt');
$file = str_replace($word, '', $file);
file_put_contents('./file.txt', $file);

    $login = "lalala";
    
    $file = __DIR__."/iki.txt";
    
    $handle = fopen($file, "r");
    while (!feof($handle)) {
        $buffer = fgets($handle, 4096);
            if($login != $buffer)
                $data[] = $buffer;
    }
    fclose($handle);    

    file_get_contents($file, $data);
    

$word = 'lalala';
$lines = explode("\n", file_get_contents('./iki.txt'));
$file = array_filter($lines, function ($line) use ($word) {
    return $line !== $word;
});

file_put_contents('./file.txt', implode("\n", $file));