Is it safe or supported to remove the local security groups that the SQL Server setup creates (SQLServer2005MSSQLUser$$MSSQLSERVER) ?

When the SQL Server setup is ran, it creates some local groups of the following format:

SQLServer2005MSSQLUser$<computer name>$MSSQLSERVER

These groups are part of the product and should not be deleted:

- Reviewing Windows NT Rights and Privileges Granted for SQL Server Service Accounts

Deleting them renders the product unsupported and part of the functionality is lost. Plus, it poses a security risk.

Specifically, after deleting these groups, it is no longer possible to install updates and Service Packs to the SQL Server product:

- SQL Server 2005 Service Pack 2 is not successfully updated when you try to install or to uninstall a security update

- Error message when you try to install a SQL Server 2005 service pack or a SQL Server 2005 hotfix package: "Error 29528. The setup has encountered an unexpected error while Setting Internal Properties"

So, to summarize, it is neither safe nor supported to delete these groups.