I would like to remove a filter your Where Class is adding – but you call do not use the getInstance pattern (many new wordpress Plugins use this!). And you are not assigning the Object to a variable.

Because of that, it’s not possible to remove_filter().

Please read this comment: https://wordpress.stackexchange.com/a/36110

And add this to your classes:

    protected static $instance = NULL;

    public static function getInstance() {
        NULL === self::$instance and self::$instance = new self;
        return self::$instance;
    }

or at least assign the Objects to a variable:

    public function initSearch()
    {
      if (!$this->isSearchAvailable()) return;

      new Join();
      new Query();
      new Request();
      new Where();
    }

Because otherwise, remove_filter f.e. for

add_filter('posts_search', [$this, 'sqlWhere'], 0, 2);

from your Search\Where class is not working in themes functions.php

I am using https://github.com/herewithme/wp-filters-extras/ now to do this, but it should not be needed anymore today.