I installed an app below and after deleting the app the features the app provides are still showing on my shopify store. its a huge inconvenience. any idea how to permanently get them off my shopify? I also have this error message showing, all jargon to me https://devcenter.heroku.com/articles/logging#view-logs
If you need to just get this done contact me with store url ,theme name, and details for pricing.
Generally you need to consult that apps developers or their documentation for installation instructions.
If that is not an option you will have to find the offending code and remove, or use a backup of your theme from before you added the app.
For future theme maintenance know shopifys added a new system to help with this called app-blocks to integrate with OS2.0 themes and uninstall more cleanly but some apps are still vintage and will leave things behind especially if you customize the theme.