Ok, back up. So presumably you first tried to delete the user properly through the SA and what happened? Were they removed and came back? was there an error?
So you can see a record in the Subscriber table (not the global subscriber table) and you can see the alias string and it tells you it can't find the record? That's pretty suprising... your DB is deeply damaged if that report is accurate. If SQL is not obeying standard query requests we've got problems.
As a test, I'd select the row in the subscriber table you can see, right click on the SubscriberObjectId column for that row, select "copy" in the pop up menu and then construct a query "DELETE FROM Subscriber WHERE SubscriberObjectID='(objectid)' where, of course, the (objectid) string is replaced with what you copied. The ObjectID value is the unique identifier for all rows in all tables so this is the definitive way to select any row in any table for an action.
If that does not remove the row then some trigger is preventing it's removal in the background (i.e. it attempts to remove the call handler associated with the user and such and it's failing so the record removal itself fails). Frankly, I've never seen this in real life on a 4.x system but technically it's possible.
