Just now, I removed a search engine hijacker, called Delta Search, from my sister's computer. Even after googling how to get rid of it I wasn't able to fix the problem. I had followed many guides telling me to uninstall it, run a virus scan, clear the cookies/cache/etc, and delete it from the default search engine. Nothing worked, and I wasn't the only one who thought they tried everything.

There was one thing, however, that I overlooked. In the settings of Google Chrome, under "On startup" you can set a certain webpage Chrome will open up to. Even though I had deleted Delta Search as my default search engine, it would still pop up because it was set as the start up page. Just delete the URL and replace it with something like https://www.google.com/ and the problem should be fixed.

Delta Search will take over all your other browsers too, such as Internet Explorer and Firefox. I was able to fix my sister's Internet Explorer the same way I did it in Google Chrome so it's pretty simple. Delta gets installed on to your computer when you download some free program that it comes bundled with.

I'm writing this out because despite all the removal guides I read, not one suggested this method. Maybe it will help out others who can't seem to fix a hijacked search engine too.
Here is one of the very informative guides I followed to help uninstall Delta Search.