如果单词有这个字母我怎么能删除单词

I must delete words if in word have letters "ц", "щ", "ы", "ь". I create this functions for need me but it works slow.

public function CheckToInsert($text)
{

 $xarfho = array("ц", "щ", "ы", "ь","қ","ӣ","ғ","ҷ","ҳ","ӯ","Қ","Ӣ","Ғ","Ҷ","Ҳ","Ӯ");

 foreach ($xarfho as $xarf) 
 {
     if (stripos($text,$xarf) !== false) 
     {
         return true;
     }
 }



 return false;

}

public function UnsetUncorrectWords($words)
{
    foreach ($words as $key => $value) 
    {
        if($this->CheckToInsert($value) == false) unset($words[$key]);
        if(strlen($value) < 3) unset($words[$key]);
    }

    return $words;
}

You may use preg_grep to get either the array items that contain a regex match, or those that do not contain a match with a PREG_GREP_INVERT flag.

So, to get all the items that have no letters of your choice, use

$xarfho = array("ц", "щ", "ы", "ь","қ","ӣ","ғ","ҷ","ҳ","ӯ","Қ","Ӣ","Ғ","Ҷ","Ҳ","Ӯ");
$wrds = array('Еыфвҷ','цӣвееп','аааа');
$pat = '/[' . implode("", $xarfho) . ']/u';
$res = preg_grep($pat, $wrds, PREG_GREP_INVERT);
// => Array (  [2] => аааа )

See the PHP demo

To get the items with the "ц", "щ", "ы", "ь","қ","ӣ","ғ","ҷ","ҳ","ӯ","Қ","Ӣ","Ғ","Ҷ","Ҳ","Ӯ" letters, use

$xarfho = array("ц", "щ", "ы", "ь","қ","ӣ","ғ","ҷ","ҳ","ӯ","Қ","Ӣ","Ғ","Ҷ","Ҳ","Ӯ");
$wrds = array('Еыфвҷ','цӣвееп','аааа');
$pat = '/[' . implode("", $xarfho) . ']/u';
$res = preg_grep($pat, $wrds);
// => Array ( [0] => Еыфвҷ [1] => цӣвееп )

See another PHP demo.

The regexps will look like /[цщы]/u where [...] is a character class that matches any char (or range of chars) defined in the pattern and the /u modifier is required since your pattern contains characters other than ASCII and the UNICODE modifier will make the regex engine correctly parse both the pattern and input strings.

I suggest to rewrite your function (or to not use a function at all) like that:

public function UnsetUncorrectWords($words)
{
    return preg_grep('~\A[^қӣғҷҳӯҚӢҒҶҲӮ]{3,}\z~u', $words);
}

preg_grep filters array items that don't match the pattern.

The pattern describes words with at least 3 characters written without the letters қ,ӣ,ғ,ҷ,ҳ,ӯ,Қ,Ӣ,Ғ,Ҷ,Ҳ,Ӯ.

Note that you can't use strlen with multibyte characters since this one returns the number of bytes, not the number of characters.