OK, lets think this through...
It says "If your app enables account creation". Well, what is an "Account"?
If your app creates an "Account", doesn't that imply that some info related to that "Account" will be sent/stored outside of the device that the app is installed on?
Because if that is not the case, and the app's operation and related info are ONLY contained on the device, then what would be the purpose of the app having an "Account"?
So, if some info of the "Account" is being stored outside of the device, then that highly suggests it is located on a cloud server, and this google requirement is basically saying that if the user wants to delete their account, all info related to that account needs to be deleted on the device *AND* the cloud server.
The requirement also states that the user should be able to delete their account via a weblink (as an alternative to doing it from the app). This shoudn't be much of a problem because you can do something like this:
1) The user clicks a weblink to delete their account.
2) The cloud server deletes the account on it's system.
3) The cloud system would then send a push notification to the app, telling it to delete all the account info.
4) If for some reason the app/device does not receive the push notification, then the next time the app tries to log into the users account on the cloud server, the server will report that the account was deleted (because there is no longer an account on the system using the ID that the app specified), causing the app to immediately delete the account info on the device.
Basically, I can't think of why an app would have and "Account" if nothing of that app is ever stored outside of the device. So, if in fact data is stored outside of the device, then google is simply saying that the "delete account" needs to be able to be initiated not only from the device, but also by using a weblink in the event that the app was uninstalled from the device, but the account (and it's possible confidential info) still exists in the cloud.