Override a class function to include a custom template

Question

I want to replace a template from a third-party plugin included by a class function with a customized one. I am trying to override that class function by extending the parent class, but for now this just is doubling the expected output. How to remove the original function? I need to remove the filter that is added in the parent class? How to do that?

The main class looks like this:

class Import_Some_Events_Cpt {

    public function __construct() {
        add_filter( 'the_content', array( $this, 'some_events_meta_before_content' ) ); 
    }

    function some_events_meta_before_content( $content ) { 
        $event_details = $this->some_events_get_event_meta( get_the_ID() );
        $content = $event_details . $content;
        return $content;
    }

    function some_events_get_event_meta() {
        //here is included the original plugin template
    }
}

My extending class is looking like this:

class Import_Some_Events_Cpt_Ext extends Import_Some_Events_Cpt {

    function some_events_meta_before_content( $content ) { 
        $event_details = $this->some_events_get_event_meta( get_the_ID() );
        $content = $event_details . $content;
        return $content;
    }

    function some_events_get_event_meta() {
        //here is included the customized template
    }
}

UPDATE

The original class Import_Some_Events_Cpt is instanciated in an other class:

class Import_Some_Events{
    private static $instance;
    public static function instance() {
        if( ! isset( self::$instance ) && ! (self::$instance instanceof Import_Some_Events ) ) {
            self::$instance = new Import_Some_Events;
            self::$instance->setup_constants();

            add_action( 'plugins_loaded', array( self::$instance, 'load_textdomain' ) );

            self::$instance->cpt    = new Import_Some_Events_Cpt();

        }
        return self::$instance; 
    }
}

This class is instanciated from a separate function:

function run_import_some_events() {
    return Import_Some_Events::instance();
}

And the above function is set to a variable:

$ife_events = run_import_some_events();

The all code is in an other file than the class I want to override.

Sorry if I make mistakes, I am not a programmer.

Answer 1

Try something like the code below:

function wpse282960_remove_filter() {
    $run_import_some_events = run_import_some_events();
    remove_filter( 'the_content', array($run_import_some_events->cpt, 'some_events_meta_before_content') );
}
add_action( 'template_redirect', 'wpse282960_remove_filter' );