For Wise for Windows Installer 6.2:

Please locate the following registry key:

1.  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID NUMBER>\Products 
Locate the Key F71449D4FC7174744AE26DDA4B05BC88 and remove it from machine, if you already uninstalled Wise for Windows Installer  6.2.

For Wise for Windows Installer 6.1:
Locate the following registry key :
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<SID>\Products\B07E0B4E3BC052E439A9F3E0A34D2AF8
and remove it from your machine if you have already uninstalled Wise for Windows Installer 6.1

For Wise for Windows Installer 6.0.223
Use the  MSIZAP tool using the following command:
msizap t[WA!] {A59AE7CD-B303-4217-AA56-FAE60359FBCD}

or delete the directory 
the {A59AE7CD-B303-4217-AA56-FAE60359FBCD} in C:\Windows\Installer directory.

Another tool you can try is the Msicu.exe which is the Windows Installer Cleanup tool.
It is found at http://support.microsoft.com/kb/290301/.

If none of the above works, then go to the following registry key and delete it:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID NUMBER>\Products 

Locate the Key DC7EA95A303B7124AA65AF6E3095BFDC and remove it from machine, if you already uninstalled WFWI 6.0.

for Wise for Windows Installer 5.21 :

Use a tool MSIZAP using the following command:
msizap t[WA!] {3AC9AB86-7A52-4327-9A17-39E5B56E32DF}
or
delete the directory
{3AC9AB86-7A52-4327-9A17-39E5B56E32DF} in the C:\Windows\Installer directory.

Another tool you can try is the Msicu.exe which is the Windows Installer Cleanup tool.
It is found at http://support.microsoft.com/kb/290301/.

If none of the above works, then go to the following registry key and delete it.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID NUMBER>\Products 
Find 68BA9CA325A77234A971935E5BE623FD and remove it from machine, if you already uninstalled WFWI 5.21.

 Use MSIZAP using the following command:

It is a commandline utility that will need the following parameter:

msizap t[WA!] {F7E301AA-A6B4-49F9-BCDD-CD96A5BC1B1A}

or delete the directory:
{F7E301AA-A6B4-49F9-BCDD-CD96A5BC1B1A} in the C:\Windows\Installer directory.

Another tool you can try is the Msicu.exe which is the Windows Installer Cleanup tool.
It is found at http://support.microsoft.com/kb/290301/.

If none of the above works, then go to the following registry key and delete it.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID> \Products\AA103E7F4B6A9F94CBDDDC695ACBB1A1

For Wise Package Studio 4.x:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID> \Products\C5CBC181BC5963D45B0C7898D0AE07C9

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\<Your SID> \Products\04A5E8D9DE2A83C45A780B6C829994C7