How can I modify or remove the PasswordHash class in XenForo to change the encryption algorithm?

Question

I am using XenForo [2.2.13]. Currently, the PasswordHash class handles the generation and verification of passwords using a custom algorithm and what I want to do is to modify that class to change or remove the encryption algorithm, but the truth is that I don't know how to do this. I would be very grateful if you could help me with this.

type here  function gensalt_blowfish($input)
{
    # This one needs to use a different order of characters and a
    # different encoding scheme from the one in encode64() above.
    # We care because the last character in our encoded string will
    # only represent 2 bits.  While two known implementations of
    # bcrypt will happily accept and correct a salt string which
    # has the 4 unused bits set to non-zero, we do not want to take
    # chances and we also do not want to waste an additional byte
    # of entropy.
    $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

    $output = '$2a$';
    $output .= chr(ord('0') + $this->iteration_count_log2 / 10);
    $output .= chr(ord('0') + $this->iteration_count_log2 % 10);
    $output .= '$';

    $i = 0;
    do {
        $c1 = ord($input[$i++]);
        $output .= $itoa64[$c1 >> 2];
        $c1 = ($c1 & 0x03) << 4;
        if ($i >= 16) {
            $output .= $itoa64[$c1];
            break;
        }

        $c2 = ord($input[$i++]);
        $c1 |= $c2 >> 4;
        $output .= $itoa64[$c1];
        $c1 = ($c2 & 0x0f) << 2;

        $c2 = ord($input[$i++]);
        $c1 |= $c2 >> 6;
        $output .= $itoa64[$c1];
        $output .= $itoa64[$c2 & 0x3f];
    } while (1);

    return $output;
}
function HashPassword($password) { $random = '';

    if (CRYPT_BLOWFISH == 1 && !$this->portable_hashes) {
        $random = $this->get_random_bytes(16);
        $hash = $this->gensalt_blowfish($random);
        return $this->crypt_private($password, $hash);
    }

    if (CRYPT_EXT_DES == 1 && !$this->portable_hashes) {
        $random = $this->get_random_bytes(3);
        $hash = $this->gensalt_extended($random);
        return $this->crypt_private($password, $hash);
    }

    $random = $this->get_random_bytes(6);
    $hash = $this->gensalt_private($random);

    return $this->crypt_private($password, $hash);
}
function CheckPassword($password, $stored_hash) { $hash = $this->crypt_private($password, $stored_hash);

    return hash_equals($stored_hash, $hash);
}

public function reverseItoA64($char)
{
    return strpos($this->itoa64, $char);
}
}