Modify WordPress plugin code from 'functions.php'

function dwqa_breadcrumb() {
            $output = '';
            if ( $term ) {
            $output .= '<span class="dwqa-sep"> &rsaquo; </span>';
            if ( is_singular( 'dwqa-question' ) ) {
                $output .= '<a href="'. esc_url( get_term_link( $term, get_query_var( 'taxonomy' ) ) ) .'">' . $tax_name . ': ' . $term->name . '</a>';//displays category: and with name
            } else {
                $output .= '<span class="dwqa-current">' . $tax_name . ': ' . $term->name . '</span>';//displays category: and with name
            }
        }

        echo apply_filters( 'dwqa_breadcrumb', $output );
    endif;
}
add_action( 'dwqa_before_questions_archive', 'dwqa_breadcrumb' );
add_action( 'dwqa_before_single_question', 'dwqa_breadcrumb' );

Above code is written in the plugin file. I want to remove $tax_name through functions.php without editing the plugin. I know how to do it when it is an array but I can't do it with variable.