Go to registry editor and navigate to the following key:

HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Explorer \ My Computer \ NameSpace \ DelegateFolders

You'll see a sub-key named {59031a47-3f72-44a7-89c5-5595fe6b30ee}. If you delete this, all of the Shared Documents folders (which are normally under the group called "Other Files Stored on This Computer" will be gone.