When you uninstall our app without an uninstalling the app from your theme first, all functions are disabled while scripts and asset files still there.
In order to remove them completely, you have to find and remove below codes/files:
Note: if you do not find any files below, it means that the app is uninstalled completely from the theme. You do no need to make any change.
Go to Themes Folder
Open layout/theme.liquid file. Then find and remove the following code
{% include 'gsc-script' %}Finally, find and remove the 5 following files