Sounds like you tried some of the tools listed as being useful to remove it.
But it gets installed as an extra feature when installing some downloaded programs. You may need to track down which program installed it. If you still have the install files, fire them up, and see which offer it as an extra, but then don't complete the install. At least you may know where it is. However, since it likely installs itself at boot-up, and likely saves a copy at shut down, deleting it won't help. Then you may need go into safe mode, and erase the offending files there.
No fun either way. I had a different one that took a combination of tricks to finally eradicate.
Search in google, and keep digging for solutions.
If it's not too inconvenient, doing a total wipe and re-install of of your os and programs might save time...