I believe he is saying to try and narrow it down which app it came from and if it is still being used.
If it doesn’t break anything you weren’t really using that code to begin with and doesn’t belong to an app you are currently using, you can probably just get rid of it.
Some low quality app developers will leave code inside of your theme.liquid file even after it has been uninstalled. There are much better methods for app developers to install code onto your website.
Cheers,