How to remove 64 bit WSUS 3.0 SP1 installation.

We should initially approach to uninstall WSUS 3.0 gracefully, but if it fails by any chance, we can follow the below mentioned steps to remove it manually. It will uninstall the WSUS completely.

1. Download the SDK to obtain MSIZAP.exe file.

2. From a command prompt, type:
For WSUS 3.0: MSIZAP T {77846B52-14C9-4fc4-BE63-FE06AF501442}

Note: If you also want to remove the old Windows Internal Database from the computer, you must use the msiexec.exe command to remove Windows Internal Database.

msiexec /x {BDD79957-5801-4A2D-B09E-852E7FA64D01} CALLERID=ocsetup.exe
Delete HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall\Windows Internal Database (if available)
Delete HKLM\System\CCS\Services\MSSQL$MICROSOFT##SSEE (if available)
Delete HKLM\Software\Microsoft\Microsoft SQL Server\MICROSOFT##SSEE (if available)
Delete %windir%\SYSMSI folder (if available)

3. From a command prompt run the following commands to delete WSUSService and WsusCertServer
sc delete wsusservice
sc delete wsuscertserver

4. Delete the following registry entries (if available)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSUS: Client Web Service Methods
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSUS: Reporting Web Service
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSUS: Server Web Methods
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSUS: Server Web Service
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSUS: Update Regulation Web Methods
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WSusCertServer
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WsusService
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Update Services

10. From a command prompt and change directory to c:\windows\microsoft.net\framework\v2.0.50727
Then type the command : aspnet_regiis -i

11. From a command prompt, type: iisreset

12. Re-run the WSUS 3.0 installation and leveraging the Deployment guide.
Deploying Microsoft Windows Server Update Services 3.0 SP1 (https://technet.microsoft.com/en-us/library/cc720507.aspx)