1. First, you need to remove the snippet that you paste in your theme.liquid. Ctrl + F this query neon-stock-info-widget and remove the whole div class.
NOTE: Please remove the above snippet of code in order to remove the app completely, prior to uninstalling the app.
2. Starting from your Shopify admin dashboard, click on the Apps tab.
3. Locate NEON, then click on the Trash icon next to it.
4. Click Uninstall. You may leave us any feedback as to why you're uninstalling NEON as well.