Thank you for reaching out to the Community! I’m happy to provide some assistance with a third-party app, to ensure this gets resolved. To confirm I’m fully understanding, the apps coding still remains within your shops theme even after it has been removed from the Shopify admin, correct?
If so, I would encourage you to contact the app developer directly. This will ensure that the Langify team takes a closer look to confirm that all coding is removed from the theme moving forward without errors. To contact the app developer, you can head to the Shopify App Store and select Support > Get Support.
Please let me know if you have any other concerns.
You should see Langify within Shopify’s App Embeds section where you’ll be able to disable Langify (don’t forget to save this setting afterward in the top right-hand corner):
Now you’ll just have to replace the whole theme.liquid code with the previously copied code e.g. via CTRL + A to select everything inside the theme.liquid and CTRL + V to paste the cleaned-up code from your clipboard.