Removed hard drive but not afp mount

I used to store my Users directory on a separate hard disk on my PowerMac G5 under Mac OSX Server 10.5. I recently upgraded to a NAS, so I removed the my hard drive /Volumes/MyDrive.

Unfortunately, I don’t think I went about it the right way. When I start up Workgroup Manager, I notice that under the Home tab for each user the old afp mounts still appear. A typical entry for the home directory of a user would be:

(None)
afp://mac.xyz.com/Users
          Full path: /Network/Servers/mac.xyz.com/Volumes/MyDrive
afp://mac.xyz.com/Users
          Full path: /Network/Servers/mac.xyz.com/Volumes/MyNAS/Users
afp://mac.xyz.com/Users/dbas
          Full path: /Network/Servers/mac.xyz.com/Volumes/MyNAS/Users/dbas

The last 2 entries are valid, since they resolve to locations on the NAS, but the first afp mount is not,as my old hard drive /Volumes/MyDrive is no longer installed.

I also notice that I am able to edit and delete the last 2 entries but not the first afp mount,as the delete and edit buttons are greyed out for that entry. So that leaves me in a quandry. I now have an afp entry which is incorrect, and which I cannot remove.

This has further repercussions. I notice that when I try to perform a network login on a client machine to the server, I get the error message:

You are unable to log in to the user account "thor" at this time

Logging in to the account failed because an error occurred.

Typically this error occurs because the home directory for a user is not available. I suspect that this is due to that errant afp entry for /Volumes/MyDrive. Indeed, on the client machine in which I tried this out, I notice that the mount

/Network/Servers/mac.xyz.com/Volumes/MyDrive

was created on the client machine, though the MyDrive directory remains empty. Similary, on that client machine when I type ‘mount’ on the command line, I get:

trigger on /Network/Servers/mac.xyz.com/Volumes (autofs, automounted)
trigger on /Network/Servers/mac.xyz.com/Volumes/MyDrive (autofs, automounted)

Thus it appears that my Mac OSX Server machine is still trying to provide a mount for this missing drive instead of the NAS.

Can someone show me how to fix this problem? How can I repair the WGM user entries for Home to remove the defunct MyDrive entry, and get my client machines to mount the NAS?

TIA for any help