Download and run the FREE version of Malwarebytes. That just might do it. https://www.malwarebytes.org/

This might help: Oursurfing Removal

Yeah, I would use bugspop1's link, then out of all its options, follow step 4 to use Malwarebytes as it's probably the more common of the malware removers.

Sad! I've spent nearly a whole day to deal with the problem weeks ago. I did not notice it until one day I wanted to search something. I was too lucky to find this post which lists detailed and free steps including deleting system files. Hope this works for you as well!

I would be reluctant to install Spyhunter mentioned in above post. Just be careful, and if anyone over the internet offers to fix your computer for a price, run. Sorry I lost my reply and have to leave the house, so this is a quick synopsis.