KIa Connect Deactivation Process PDF
Personally I would do the app first, then the car and finally reset the car media system to default to remove your data from the car.

 

So I guess the answer is, do it in both then

 

That is how I would approach it,I dumped Kia Connect app earlier this year, so I am not completely sure.

Edit: I wouldn't do it until you are ready to move the car on.

 

Found this kia help page.

https://www.kia.com/content/dam/kwcms/au/en/files/service/kia-connect-activation-deactivation.pdf

FAQ | Kia Connect

connect.kia.com

 

For future generations, doing the above, still leaves your user profile on the car. Be sure to delete that too.

 

Go on to head unit, Connect section. Delete user. Is all you need to do.

If you are planning on another Kia then back up profile in APP & you can then load that on your new Kia.
If not getting a Kia, then just delete Connect from phone.

 

I did this, but the user profile was still there. I had to go into profiles, and delete that as well. I don't think that it stores much, other than name, picture and some settings. Once I deleted this, for example, the chair started moving. So it's probably just chair, mirror etc settings in it, probably not a big deal if not done, but I prefer to leave no trace.

All good though, I think I am gone from the car.

 

Kia must have changed things on ccNC head unit. As old cars never did save profile.

 

This is why I said, remove on app, remove on car and the reset the head unit to default, but nobody was listening.