Although you have gone ahead and deleted the app from your store, it looks like the app has left over some residual code in your theme.
As this is a third-party app that is not listed in our app store, your best bet here would be to reach out to the app developers themselves and get them to check if this is the case. They will be able to provide more context and would be best equipped to help you get this resolved. For your convenience, I have listed their support page here.
Once you have spoken with them, and if they cannot find the source of the issue, I would then suggest contacting the developer of your theme to assist here. If your theme is one that is listed on our theme store here, you should be able to find their contact details for support by searching the theme's name and scrolling down to 'Support and documentation'.
I hope this helps, have an awesome day!
Maz | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog