You said both if you have access through separate accounts? Did you have it installed and then send her an invite to join the account? Which is how it should have occurred.
Any changes made on your phone in the app reflect equally in her phone app. And vice versa.
Ensure you attempt to remove the app the way it was listed above by @pizzinini.
FYI, it is not normal to get that error when attempting to remove an app from the mobile app. It’s a bug in the system.
If you can not delete the app through the API, go into the app and remove all of the setting by tapping on each option and deleting them. Basically leaving the app empty.
Once you have done that, go back to the market place and run the install on the app again. Yes, this will probably give you two instances of the ago, but with all of the settings removed from one, the other should work. I’ve had to do this before.
Then, send an email to support asking them to remove the empty smart app from your system.