While combofix is an extremely useful application, on rare occasions it can cause further problems to your PC and needs to be uninstalled. If combofix locks up, please try and let it run for an hour atleast before killing combofix.exe processes.
To kill the process, simply launch Windows task manager (ctrl + alt + del) and end the task, or right click on the task and select ‘Go to process’ and press the ‘End Process’ button. As this can often leave random executable files running we urge you to give combofix time to complete prior to aborting the process. If you do have to kill combofix using the above technique, be sure to reboot or your internet may not work!
Combofix is very easy to uninstall and can be done using a cleanup tool known as OTC by Oldtimer.
How to uninstall combofix
1) Download OTC by OldTimer (a quick google search will find you the file, save it to your desktop).
2) Run the OTC.exe file and click on the ‘Cleanup’ button to uninstall combofix.
3) At the end of the process OTC will prompt you to reboot. Reboot your PC and all of combofix and its associates files and folders that it creates including the setup file combofix.exe will be removed. OTC.exe even removes itself after the reboot has been completed.
This is how to uninstall combofix as of April 2012, as the previous method using combofix.exe -u is no longer supported.