Hi,

You can change the portfolio slug by adding the following code to the functions.php file of the Kanik/Kanikchild theme.

function change_portfolio_post_type_slug() {
    if ( post_type_exists( 'portfolio' ) ) {
        $post_type = get_post_type_object( 'portfolio' );
        $post_type->rewrite['slug'] = 'project';
        $post_type->rewrite['with_front'] = false;
        register_post_type( 'portfolio', (array) $post_type );
    }
}
add_action( 'init', 'change_portfolio_post_type_slug', 20 );

Feel free to ask for anything you need.

Kind Regards