The users that are a member of the HPC "User" role are coming from the local Users group in the Local Users and Groups MMC snap-in on both head nodes. Likewise, the members of the HPC “Administrator” role are coming from the local Administrators group from both head nodes. The members of these local security groups in the Local Users and Groups of the two head nodes are automatically "repaired" and this causes the deleted user to reappear.
This problem is resolved in HPC Pack 2008 R2 Service Pack 1 (SP1). Install HPC Pack 2008 R2 SP1 on all nodes and then attempt to remove the user names from the Users view of the HPC Cluster Manager.
Here's the link to download HPC Pack 2008 R2 SP1:
For Windows HPC Server 2008:
A PowerShell commandlet patch has been released that allows you delete user accounts. Please see the following knowledge base article for more information:
2459872 Removed user or administrator account reappears in an HPC Pack 2008 cluster after a while if you configure a pair of High Availability or failover head nodes
Article ID: 2476794 - Last Review: Jan 19, 2011 - Revision: 1