When trying to remove a customer or subscription, you may get this error message in Plesk:
Unable to find service node for web service on domain with id=xxx
This was supposed to be fixed in 10.4.4 MU #13 but isn’t in all cases. I hit this error and the cause turned out to be because the subscription had no IP address assigned to it.
To fix this, go into the Hosting Settings of the subscription. Select an IP address, you’ll also have to reset the password.
Once you do this, you should be able to remove the customer and subscription.