After you uninstall the app, make sure you do these 4 steps:

1) Edit theme.liquid
search and remove the line: {% include "tabarnapp_cm" %}
It should be right before < /head >

2) After step 1 was done
delete theme.tabarnapp_backup.liquid (this file was a backup of theme.liquid before we added our code, but the main file might of changed since then so don't use it. We make this backup in case the initial write fails)

3) remove the script tag file: delete assets/tabarnapp_cm.js

4) remove the snippet that was added to theme.liquid
Make sure you first removed the {% include "tabarnapp_cm" %} from theme.liquid file first. After you double checked, remove snippets/tabarnapp_cm.liquid file

Done.