Removing entries from the Places menu

[Cameron Hutchison]

How do I remove entries from the Places menu? I've accumulated some
network servers that I want to remove but can find no way of doing it.

If I go to "NetworkServers" and try and delete them from there, I get an
error dialog saying:
  Error "Operation not permitted" while deleting "network:...-coopers".
  Would you like to continue?
             [Cancel] [Retry]

Clicking [Retry] just brings up the same dialog.

I assume the entries in the Places menu are stored in files somewhere,
but where? Perhaps I can delete them manually?

Thanks