Remove an action added within a class in a WordPress plugin

I finally managed to make it work :

function remove_searchfield() {

    $tag = 'epl_frontend_search_field_select'; // the name of the hook
    $function = 'render_select'; // the function you wish to remove
    $priority = 10; // must be an integer

    remove_action ( $tag, array( Easy_Property_Listings::instance()->search_fields, $function ), $priority);
}
add_action( 'init', 'remove_searchfield');

Thanks Jacob for the help 😉