To completely uninstall Exchange Server from SBS:
01. Mount the SBS CD-ROM.
02. Use Control Panel / Add/Remove Programs / Microsoft Small Business Server and click Add/Remove.
03. Click Next on the Company Information screen.
04. On the Select Components window, uncheck Microsoft Exchange Server.
05. Let Setup remove Exchange server. Reply No when prompted to reinstall the client software.
06. When complete (or you receive an error), use Control Panel / Services to Stop the Microsoft Exchange System Attendant, which should stop all the Exchange services.
07. Use regedt32 to navigate to HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services and delete the following keys (and sub-keys):
08. Browse to HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Exchange and delete the Exchange key and sub-keys.
09. Navigate to HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/EDB and delete EDB and sub-keys.
10. Use WinFile to delete the EXCHSRVR folder on each of your disk drives.