You can remove by visiting Appearacnce → Customize, WooCommerce → Store Notice, Uncheck the Enable store notice checkbox and click the Publish button.

If still doesn't work, please clear cache for the website and looks, it will be fixed.

If there is still issue use below css to hide this panel.

.woocommerce-store-notice{

display: none;

}

Add the above code in your theme css file.