Resolution

The user ID(s) will need to be manually set to inactive then deleted within the CM Full client.
Using a list of User IDs known to be Disabled in EERP a site administrator with ADMINS access to content manager can:

Log into the Content Manager full client.
Click on Administration > Security Manager > Users
Click on the Show Inactive Users button from the command ribbon.
Search for each user to be removed, select the users ID, then click Remove Entry.
Repeat step 4 for each user to be removed.
Once all users have been removed sort the list of all users by clicking on the title of the Active column to sort all inactive IDs to the top.
Click the first ID+Shift then click the last ID to select all Inactive IDs, then click Remove Entry.
Refresh the list and sort again by the Active column to ensure all Inactive IDs have been removed.

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