This is Oswald, a Guru here at Shopify!
If you are still experiencing the issue you have mentioned, don't hesitate to contact us via phone or live chat at the following link (https://help.shopify.com/questions) and we will be able to further look into your account for the app that you had previously installed and ensured that the code was fully removed.
If you have any other questions, feel free to reach out to the Guru team. :)
Oswald | Shopify Guru