Open Exchange 2007 management shell (CMD line) and type following commands:
Get-PublicFolder -server xxxxx "\" -Recurse -ResultSize:Unlimited | Remove-PublicFolder -server xxxxx
-Recurse -ErrorActionilentlyContinue
Get-PublicFolder -Server xxxxx "\Non_Ipm_Subtree" -Recurse -ResultSize:Unlimited | Remove-PublicFolder
-Server xxxxx -Recurse -ErrorActionilentlyContinue
Replace xxxxx with your Exchange server name in the above command.
in ADSIEdit, go to Configuration, Configuration, Services, Microsoft Exchange, First
Organization, Administrative Groups, Exchange Administrative Group, Servers, Servername, Information Store, First Storage
Group. Then on the right hand pane, highlight the Public Folder Store and Delete it. This performs basically the
same function as the cmdlet does, or removing it via the Exchange Management Console