1. Go to "Start" menu, then to "Control Panel" and select "Add/Remove Programs"
2. Search for "QuickTest Add-in For Quality Center” and click on "Remove", then follow the wizard to perform the uninstallation of the add-in
3. Open the Windows Registry Editor (Start > Run > type “regedit” > Ok)
4. Navigate to following paths and delete the icon called “QuickTest Add-in for Quality Center”:
   
   - HKEY_CURRENT_USER\Software\Mercury Interactive\
   - HKEY_LOCAL_MACHINE\Software\Mercury Interactive\
   
   
5. Browse to "C:\Program Files\<Mercury or HP>\" and delete the “QuickTest Add-in For Quality Center” directory
6. Browse to "C:\Program Files\Common Files\Mercury Interactive\Quality Center" and delete the contents of such directory
7. Browse to QC temp folder called TD_80 under machine's temp directory (Start > Run > type “%temp%\TD_80” > Ok) and delete the contents of such directory

After having perform steps above and QuickTest Professional is already installed on machine the add-in can be reinstalled