So, if you want a delete an app in Splunk, you could always delete every view in that app.
The app would live but there would be nothing in it.
Trying to achieve a better outcome that that.
I want to know how to delete it completely (again, NOT DISABLE IT by going to Splunk > Manager > App, actually delete it)
This is my confirmation : Go to App> on the top right corner of the screen, I can no longer see it.
I actually tried to go to $SPLUNK_HOME/etc/apps/ and deleted the folder for that app and restarted Splunk and that did not exactly work out (I had to restore the backup because Splunk started doing some weird crap)
Do not delete the search apps (that contains all the manager pages, and default view for the other apps)
Otherwise you can delete the folder to completely remove the app. But user may still have private objects in their profiles.