Step 1:
Disable and Stop the following services in Start>Administrative Tools>Services
-Microsoft Single Sign-on Service
-Office SharePoint Server Search
-Windows SharePoint Services Administration
-Windows SharePoint Services Search
-Windows SharePoint Services Timer
-Windows SharePoint Services Tracing
-Windows SharePoint Services VSS Writer
Step2:
Delete the following registry hives in Start>Run>Regedit.exea) HKLM\Software\Microsoft\Office Server\12.0
b) HKLM\Software\Microsoft\Shared Tools\Web Server Extensions\12.0
For 32bit:
c) HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall\OSERVER
For 64bit:
c) HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\OSERVER
Step3:
Delete the following folders
a) C:\Program Files\Microsoft Office Servers\12b) C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12
c) C:\Program Files\CommonFiles\Microsoft Shared\SERVER12 (if u find this folder then delete it)
After performing above steps u find Moss uninstall from your machine
Step4.
Restart the server and start Moss installation again.After an installation, if u get error to run Sharepoint Product and technologies configuration wizard then you can uninstall Moss from control panel or by running setup file, now it will completely remove Moss.